The converted Gentiles will become Israel. In fact, the Gospel is to be restored through the “Gentiles” in the last days. 3 Ne. 21:6:
“For thus it behooveth the Father that it should come forth from the Gentiles, that he may show forth his power unto the Gentiles, for this cause that the Gentiles, if they will not harden their hearts, that they may repent and come unto me and be baptized in my name and know of the true points of my doctrine, that they may be numbered among my people, O house of Israel.”
Once numbered among Israel, the converted will reflect on the many centuries of persecution that have been heaped on Israel. They will reflect with shame upon the way Israel has been treated.
In the end, despite persecution and rejection, it will be Israel herself which will be triumphant. Those who “wait upon the Lord” and join in His cause, will not be “ashamed.” Rather, the persecutors will find themselves bowing in shame at how they treated the Lord’s anointed.
From these images we again see that Nephi had a visionary understanding of our day. He chose the words of Isaiah to convey the things he saw and understood. The Lord’s people will gain final vindication after first enduring the difficulties of persecution and the trials of preaching the Gospel to a hostile world. But when the work finishes, it will be those who rejected the truth who will feel shame. And it will be those who accepted the Gospel who will feel triumph. However different it may appear on a temporary basis, in the end it will play out as vindication for the Lord’s chosen people.