I’ve heard this question asked before and also two different answers: Yes and No. What does YHWH say?
First we must know, what truly is salvation? The word ‘salvation’ stems from the latin word ‘salvare’, meaning ‘to make safe or secure‘.
A good example is:
(WEB) Exodus 14:13–
13 Moses said to the people, “Don’t be afraid. Stand still, and see the salvation of YHWH, which he will work for you today: for the Egyptians whom you have seen today, you shall never see them again. 14 YHWH will fight for you, and you shall be still.”
2 Chronicles 20:14-17 —
14 Then YHWH’s Spirit came on Jahaziel the son of Zechariah, the son of Benaiah, the son of Jeiel, the son of Mattaniah, the Levite, of the sons of Asaph, in the middle of the assembly; 15 and he said, “Listen, all Judah, and you inhabitants of Jerusalem, and you, king Jehoshaphat. YHWH says to you, ‘Don’t be afraid, and don’t be dismayed because of this great multitude; for the battle is not yours, but God’s. 16 Tomorrow, go down against them. Behold, they are coming up by the ascent of Ziz. You will find them at the end of the valley, before the wilderness of Jeruel. 17 You will not need to fight this battle. Set yourselves, stand still, and see the salvation of YHWH with you, O Judah and Jerusalem. Don’t be afraid, nor be dismayed. Go out against them tomorrow, for YHWH is with you.’”
I encourage you to revisit the entire chapter of Exodus 14 and 2 Chronicles 20 for context.
The children of Israel has been and will be the prime example of YHWH’s salvation. Other nations might not experience it on the same level, it won’t be as glorious of a story of overcoming, but that doesn’t exclude them entirely from an experience of it.
Importantly, just as the children of Israel trespassed against YHWH and were brought under judgement, so will the nations experience judgement for the treatment of the children of Israel. YHWH is fair though; after the nations are brought under judgement and some decide to follow Israel and keep YHWH’s laws and statues, would not YHWH offer life to them too? Some nations are “marked” and they will not serve no matter how much hardship YHWH will bring down on them. YHWH usually does make physical examples of choices of obedience and disobedience for even the most simple of minds to understand.
Now what has YHWH said on this matter? People can believe what they want but what YHWH says goes for all eternity.
Isaiah 66:18-23 —
18 “For I know their works and their thoughts. The time comes that I will gather all nations and languages, and they will come, and will see my glory. 19 “I will set a sign among them, and I will send those who escape of them to the nations, to Tarshish, Pul, and Lud, who draw the bow, to Tubal and Javan, to far-away islands, who have not heard my fame, nor have seen my glory; and they shall declare my glory among the nations. 20 They shall bring all your brothers out of all the nations for an offering to YHWH, on horses, in chariots, in litters, on mules, and on camels, to my holy mountain Jerusalem, says YHWH, as the children of Israel bring their offering in a clean vessel into YHWH’s house. 21 Of them I will also select priests and Levites,” says YHWH. 22 “For as the new heavens and the new earth, which I will make, shall remain before me,” says YHWH, “so your offspring* and your name shall remain. 23 It shall happen that from one new moon to another, and from one Sabbath to another, all flesh will come to worship before me,” says YHWH.
The word ‘flesh’ (H1319), ‘basar’ in Hebrew, is used the same way in Isaiah 66:23 as it is used in Genesis 6:17, for instance:
17 I, even I, do bring the flood of waters on this earth, to destroy all flesh having the breath of life from under the sky. Everything that is in the earth will die.
It is clear that whomever survives the judgement that YHWH places upon the nations, will be worshipping before YHWH and will be serving Israel as servants and tributaries.
To pose a simple question, how can the children of Israel be a light unto the nations if no other nations exist after judgement?
Isaiah 49:1-3 —
1 Listen, islands, to me. Listen, you peoples, from afar: YHWH has called me from the womb;
from the inside of my mother, he has mentioned my name. 2 He has made my mouth like a sharp sword.
He has hidden me in the shadow of his hand. He has made me a polished shaft. He has kept me close in his quiver. 3 He said to me, “You are my servant, Israel, in whom I will be glorified.”