Be careful my friend, this sounds like replacement theology. God’s covenant with Abraham was unconditional. There is indeed a special role for Israel in God’s salvation plan. The Jews were and are God’s chosen people - he chose (not by merit, by grace) to use them to teach the world about Him and the difference between holy and unholy and about the coming of the Messiah. While are you correct that God extended his grace to all (jew and gentile) who come to believe in Him through Christ, He did not abandon his covenant with Israel. This is what Romans 11 is telling us - after the full alotment of Gentile come in “all Israel will be saved” (not all Jews of all time, as some believe, but I believe he will cause that remnant to “see” and come to faith, which is consistent with zechariah when it says in the end times they will mourn for the one whom they have pierced and call on the name of the law).
As to God’s plan for those he has willed to be blind - God is merciful and this is a mystery to us.
But - the Church has not replaced Israel in terms of being the “chosen people” - we are just, together with Israel, God’s children and with all believers (Jew and Gentile) part of the mystical body of Christ.
Blessings,
Brian