I am hand writing the bible, and so far, I am up to Genesis 37.
I’ve noticed this statement three times:
“all the nations of the earth will be blessed”

Genesis 18:16-18
¹⁶ Then the men got up from there and looked down over Sodom. Abraham was walking with them to send them off, ¹⁷ when Elohim said, “Should I keep secret from Abraham what I am about to do, ¹⁸ seeing that Abraham will most certainly become a great and mighty nation and in him all the nations of the earth will be blessed? 

Genesis 22:17-18
I will richly bless you and bountifully multiply your seed like the stars of heaven, and like the sand that is on the seashore, and your seed will possess the gate of his enemies. ¹⁸ In your seed all the nations of the earth will be blessed—because you obeyed My voice.”

Genesis 26:4
I will multiply your seed like the stars of the sky and I will give your seed all these lands. And in your seed all the nations of the earth will continually be blessed, ⁵ because Abraham listened to My voice and kept My charge, My mitzvot, My decrees, and My instructions.”

So I am pondering this idea…
Exactly how are all the nations of the earth blessed by Israel?
We’ve had thousands of years go by since these statements were made.  What evidence do we have to show that all the nations have been blessed?

Here is my speculative guess on this matter:
We see evidence in scripture that some people are scorned by Yahuah.

1.  The patriarchs were told not to take wives for themselves from the people of Canaan.
Genesis 24:3
…so that I may make you take an oath by Adonai, the God of heaven and the God of earth, that you will not take a wife for my son from among the daughters of the Canaanites among whom I am dwelling.
Genesis 28:1
So Isaac called for Jacob, blessed him, commanded him and said to him, “Don’t take a wife from the daughters of Canaan.”
Genesis 28:6
Now Esau saw that Isaac blessed Jacob when he sent him to Paddan-aram to take for himself a wife from there, when he blessed him and commanded him saying, “Don’t take a wife from the daughters of Canaan.”
Deuteronomy 7:3
You are not to intermarry with them—you are not to give your daughter to his son, or take his daughter for your son. 

2.  In the New Testament, we see Messiah Yeshua ignore the woman from Canaan, and He called her a dog and told her she is not worthy to have what is for the children of Israel.
Matthew 15:23-26
But He did not answer her a word. And when His disciples came, they were urging Him, saying, “Send her away, because she keeps shouting at us.”
²⁴ But He responded, “I was sent only to the lost sheep of the house of Israel.”
²⁵ So she came and got down on her knees before Him, saying, “Master, help me!”
²⁶ And answering, He said, “It’s not right to take the children’s bread and throw it to the dogs.”

3.  We see in scripture that Yahuah hates the Edomites, the line of Esau, which was mixed with the line of Ishmael.
Malachi 1:2-4
—it is the declaration of Elohim—
“Yet I loved Jacob ³ and Esau I hated.
I made his hills a wasteland
and gave his inheritance to jackals of the wilderness.”
⁴ For Edom may say,
“We have been beaten down,
but we will return and rebuild the ruins.”
Thus Elohim-Tzva’ot says:
“They may rebuild but I will tear down.
They will be called a wicked territory,
the people Elohim denounced forever.
Obadiah 1:18
while the house of Esau will be straw—
they will set them on fire and consume them.
So there will be no survivors of the house of Esau.”
—for Elohim has spoken.
Romans 9:13
As it is written, “Jacob I loved, but Esau I hated.”

4.  In Matthew 23, we see what Yeshua Messiah thinks of the ruling religious class during His time on earth:
Matthew 23:13-33
“But woe to you, scribes and Pharisees, hypocrites! Because you shut up the reign of the heavens before men, for you do not go in, nor do you allow those who are entering to go in.
“Woe to you, scribes and Pharisees, hypocrites! Because you eat up widows’ houses, and for a show make long prayers. Because of this you shall receive greater judgment.
“Woe to you, scribes and Pharisees, hypocrites! Because you go about the land and the sea to win one convert, and when he is won, you make him a son of GĕHinnom twofold more than yourselves.
“Woe to you, blind guides, who say, ‘Whoever swears by the Dwelling Place, it does not matter, but whoever swears by the gold of the Dwelling Place, is bound by oath.’ Fools and blind! For which is greater, the gold or the Dwelling Place that sets the gold apart? And, ‘Whoever swears by the slaughter-place, it does not matter, but whoever swears by the gift that is on it, is bound by oath.’
Fools and blind! For which is greater, the gift or the slaughter-place that sets the gift apart?” “He, then, who swears by the slaughter-place, swears by it and by all that is upon it. “And he who swears by the Dwelling Place, swears by it and by Him who is dwelling in it.
“And he who swears by the heaven, swears by the throne of Elohim and by Him who is sitting upon it.
“Woe to you, scribes and Pharisees, hypocrites! Because you tithe the mint and the anise and the cumin, and have neglected the weightier matters of the Torah: the right-ruling and the compassion and the belief. These need to have been done, without neglecting the others. “Blind guides – straining out a gnat and swallowing a camel!
“Woe to you, scribes and Pharisees, hypocrites! Because you clean the outside of the cup and dish, but inside they are filled with plunder and unrighteousness. “Blind Pharisee, first clean the inside of the cup and dish, so that the outside of them becomes clean too.
“Woe to you, scribes and Pharisees, hypocrites! Because you are like whitewashed tombs which outwardly indeed look well, but inside are filled with dead men’s bones and all uncleanness.“So you too outwardly indeed appear righteous to men, but inside you are filled with hypocrisy and lawlessness.
29“Woe to you, scribes and Pharisees, hypocrites! Because you build the tombs of the prophets and decorate the monuments of the righteous, and say, ‘If we had lived in the days of our fathers, we would not have taken part with them in the blood of the prophets.’ Thus you bear witness against yourselves that you are sons of those who did murder the prophets – and you fill up the measure of your fathers! “Serpents, brood of adders! How would you escape the judgment of GĕHinnom?

4.  We are told in Genesis 3:15 there are different “seeds” upon the earth – his (Satan’s) seed and her (Eve’s) Seed.
Genesis 3:15
I will put animosity
    between you and the woman—
        between your seed and her seed.
    He will crush your head,
        and you will crush his heel.
The concept of ‘his seed’ and ‘her Seed’ is the reason why Noah’s flood occurred.  It is the reason Joshua and Caleb were commanded to kill all living beings when they entered the promise land.  But this is a whole other study involving genetics…

Seeker-friendly, mainstream Christian doctrine teaches that everyone is loved, that everyone is acceptable to Yahuah.
“Jesus loves me, this I know, for the bible tells me so.”
Who hasn’t heard this song at some point in their life?
But the scriptures I quoted above show this song is not the truth.
There are people upon the earth in ancient times that were not acceptable to Yahuah.  There were people upon the earth during Messiah’s time that were not acceptable to our Savior.

But back to the original question…
How will all the nations of the earth be blessed by Israel?

If we study scripture, and study the history of the people of Israel, the children of Elohim, we see this:
The nation of Israel split into two kingdoms; the southern kingdom of Judah and the northern kingdom of Israel>
Both kingdoms strayed from the Word and were punished for it (punishment is given in Ezekiel 4).
The kingdom of Judah repented and partially turned back to Yahuah.
However, the kingdom of Israel did not repent, and they were divorced from the covenant and scattered among all the nations.
Jeremiah 3:8
“And I saw that for all the causes for which backsliding Yisra’ĕl had committed adultery, I had put her away and given her a certificate of divorce…”
Deuteronomy 28:64
64“And יהוה shall scatter you among all peoples, from one end of the earth to the other, and there you shall serve other mighty ones, which neither you nor your fathers have known, wood and stone.
Leviticus 26:33
33‘And I shall scatter you among the nations and draw out a sword after you. And your land shall be desert and your cities ruins,
Deuteronomy 4:27
27“And יהוה shall scatter you among the peoples, and you shall be left few in number among the nations where יהוה drives you.
Psalms 106:26-27
26So He lifted up His hand in an oath against them, To make them fall in the wilderness, And to make their seed fall among the nations, And to scatter them in the lands.
Jeremiah 9:16
16“And I shall scatter them among the nations, whom neither they nor their fathers have known. And I shall send a sword after them until I have consumed them.”
[This is just a small sampling of scriptures – there are many more that describe the scattering of Israel throughout the world]

Again, I ask, how does this bless the nations?
In Ezekiel 4, the duration of Israel’s punishment is given as 390 years.  But in Torah, one who does not repent is given seven times the original punishment. Since Israel did not repent, their 390 year punishment became 2730 years!!

What happens if a people group is scattered among all the nations for 2730 years?  They mix with those nations.  They take wives, build families, have children. They assimilate…
And that is how all the nations of the world have been blessed, in my opinion!!
If there were nations and people groups who were not acceptable to Yahuah, but the people of Yahuah (the kingdom of Israel) were scattered among them —- is this a blessing?
Well, if Yahuah were going to leave Israel scattered and never restore them, then no, it would not be a blessing.
But what does scripture tells us?

Again from Matthew 15:24 quoted above, Messiah said this:
²⁴ But He responded, “I was sent only to the lost sheep of the house of Israel.”

Messiah came for His lost sheep…
The scattered people of the kingdom of Israel!!
Is there any other scripture that speaks of the restoration of these people, from among the nations?
Yes, too much to list here!!

Jeremiah 16:14:20
14“Therefore see, the days are coming,” declares יהוה, “when it is no longer said, ‘יהוה lives who brought up the children of Yisra’ĕl from the land of Mitsrayim,’
15but, ‘יהוה lives who brought up the children of Yisra’ĕl from the land of the north and from all the lands where He had driven them.’ For I shall bring them back into their land I gave to their fathers.
16“See, I am sending for many fishermen,” declares יהוה, “and they shall fish them. And after that I shall send for many hunters, and they shall hunt them from every mountain and every hill, and out of the holes of the rocks.
17“For My eyes are on all their ways; they have not been hidden from My face, nor has their crookedness been hidden from My eyes.
18“And first I shall repay double for their crookedness and their sin, because they have defiled My land with the dead bodies of their disgusting matters, and have filled My inheritance with their abominations.”
19O יהוה, my strength and my stronghold and my refuge, in the day of distress the nations shall come to You from the ends of the earth and say, “Our fathers have inherited only falsehood, futility, and there is no value in them.”
20Would a man make mighty ones for himself, which are not mighty ones?

Isaiah 49:6
He says, “It is too small a thing that You should be My Servant To raise up the tribes of Jacob and to restore the preserved ones of Israel; I will also make You a light of the nations So that My salvation may reach to the end of the earth.”

Deuteronomy 30:1-5
1“And it shall be, when all these words come upon you, the blessing and the curse which I have set before you, and you shall bring them back to your heart among all the nations where יהוה your Elohim drives you, 2and shall turn back to יהוה your Elohim and obey His voice, according to all that I command you today, with all your heart and with all your being, you and your children, 3then יהוה your Elohim shall turn back your captivity, and shall have compassion on you, and He shall turn back and gather you from all the peoples where יהוה your Elohim has scattered you. 4“If any of you are driven out to the farthest parts under the heavens, from there יהוה your Elohim does gather you, and from there He does take you. 5“And יהוה your Elohim shall bring you to the land which your fathers possessed, and you shall possess it. And He shall do good to you, and increase you more than your fathers.

[And there are so many more verses describing the gathering of Israel from among the nations]

This is my conclusion, my summary…
There were “his seed” upon the earth as we are told in Genesis 3:15.
Clues throughout scripture indicate there were people on earth unacceptable to Yahuah our Creator.  Those people are obviously “his seed” and not “her Seed.”
The scattering of the house of Israel among every nation of the earth allowed Yahuah’s chosen people to intermix with unacceptable people.  And thousands of years later, when Yahuah gathers His house of Israel, they will be taken from all the nations.
It is my belief that this is how “all the nations of the earth” have been and will be blessed through the chosen people of Israel.

What if the people of Yahuah, the people of the kingdom of Israel, never strayed and never wandered away from the ways of Yahuah?
What if the kingdom of Israel had never been scattered among the nations?
Would those other people groups that were not acceptable to Yahuah have had the chance to become His people?
Was the intermixing with the people of the kingdom of Israel what allowed them to become acceptable to Yahuah our Creator?
I am speculating that this is how all the nations of the world were blessed by Israel, as was stated three times in the book of Genesis.
Am I 100% right about this?
I can’t say that with certainty.
But the scriptures I’ve presented here show this idea might very well be true!!