Intersting you quote the Jewish scriptures....time and time again we see the following, in the very next chapter:
Isaiah 56: 6 And foreigners who bind themselves to the LORD to serve him, to love the name of the LORD, and to worship him, all who keep the Sabbath without desecrating it and who hold fast to my covenant-
7 these I will bring to my holy mountain and give them joy in my house of prayer. Their burnt offerings and sacrifices will be accepted on my altar; for my house will be called a house of prayer for all nations."
And many peoples shall come, and say: "Come, let us go up to the mountain of the Lord, to the house of the God of Jacob; that he may teach us his ways and that we may walk in his paths," for out of Zion shall go forth the law, and the word of the Lord from Jerusalem. (Isaiah 2:3)
Jer 16:19 O LORD, my strength and my fortress, my refuge in time of distress, to you the nations will come from the ends of the earth and say, "Our fathers possessed nothing but false gods, worthless idols that did them no good.
Zech 8:23 Thus saith the LORD of hosts; In those days it shall come to pass, that ten men shall take hold out of all languages of the nations, even shall take hold of the skirt of him that is a Jew, saying, We will go with you: for we have heard that God is with you.
The nations dont becomes Christians in the end days. Messiah teaches the nations about G-d, His ways, the law, and His ordinances...says so plainly.
That reads as an assumption based on biases.
The OT certainly does NOT PRECLUDE that, linguistically, theologically, in any respect.
It is only biases about the OT that insist otherwise.
It is CONCEIVABLE that Almighty G_d COULD implement something different than either TRADITIONAL JEWISHNESS OR CHRISTIANITY.
I do NOT believe He will—but HE COULD. He could manage it without violating any of the OT.
I can certainly manage it merging Judiasm and Christianity under the Messiah Yeshua.