Jewish prophecies speak about the Gentiles (and their blessing of eternal life), but they speak to the Jews, through whom salvation came to the Gentiles (Rom 11:11).
In my opinion, establishing the basis for the concept concerning the distinctions between Israel and the Church could be in how one defines "the new testament (covenant) in My blood" (Luke 22:20). It is my present understanding that the new covenant in Christ's blood is a covenant which is not between man and God, as the Decalogue (Ten Commandments) was with the nation Israel. It is a covenant between the Father and the Son (made in eternity, before creation), of which man is only a recipient ("everlasting covenant" - Heb 13:20, 21). I believe this covenant has been accurately summed up in the concept that the Father would raise His Son from the dead when He died to atone for sin in believers.
Thus, when the Lord Jesus was revealing it to the Jews (who are first in everything spiritual), the word "new" designed a dual intention concerning chronologically and application: chronologically "new" because it had yet to be brought forth in time, and "new", in that it was different from the old (old--conditional; new--unconditional).
To the Gentile, "new" designs a single intention concerning chronology only, because the Gentile never has and never will need to enter a covenant between them and God, but has entered the covenant between the Father and the Son (Everlasting Covenant), same now as the believing Jew.
The Millennium Jew (Jews who have yet to believe in Jesus) new covenant will also be everlasting (same as the believing Christian Jew) and will not be as the old covenant (Jer 31:32), where they could not avoid "braking" it (also v 32), because it requires God "causing" (Eze 36:27) them to keep His statutes and laws--through putting His Spirit in them (again Eze 36:27), same as Christians (Jew/Gentile) now (Gal 5:17).
This concept has other implications that I'm still researching to understand, which may be resolved as we continue to share with one another and correspond with what the Lord gives us to use. I would rather learn and accept a truth that may conflict with my present understanding concerning Scripture doctrine, than to worry about being embarrassed from not having an explanation for a concept or belief. One of my motives for sharing my beliefs is to as much as possible, learn truth, because the Spirit teaches through us all.
For Christ’s Sake (Eph 4:32) <><
The Christian life is not our living a life like Christ, or our trying to be Christ-like, nor is it Christ giving us the power to live a life like His; but it is Christ Himself living His own life through us; 'no longer I, but Christ. -MJS