Yes, St. Paul writes in Romans 11 that Israel will be converted, but we cannot know the exact meaning of this conversion.
I think it must not be that 100% of the entire Jewish people who will live on earth at that time when Christ will come will convert completely. We don’t know. It could be that the expression "Israel will convert" means the majority of these people, probably.
This, at least the majority, is suggested by the letter to the Romans. It would correspond to the mercy of God for his first chosen people in the Old Testament, bringing them to the fullness of the truth, which is Christ, the only Savior. For the sake of this truth, God made a covenant with the people of Israel in the Old Testament, a covenant for Christ, that they will recognize Christ.
Dear visitors of Gloria Dei and all who have already written or who will write a personal message to me. I am grateful for your attention, your kindness, for your spiritual support and especially for your sacrifices and prayers for me. God may reward you!