Thus says YHWH: If I have not established my covenant with day and night and the fixed order of heaven and earth, then I will reject the offspring of Jacob and David my servant and will not choose one of his offspring to rule over the offspring of Abraham, Isaac, and Jacob. For I will restore their fortunes and will have mercy on them.
Jeremiah 33:25-26

God's covenant with Israel is just as certain and everlasting as his covenant with Israel. God can't utterly reject Israel, because covenant-breaking isn't part of his character. He WILL restore the physical descendants of Jacob alongside those who have been adopted into the house of Israel by faith.