In Jeremiah 31:36 God says the Jewish people will continue to be “a nation before Me forever.”
Which underscores my view that God’s Covenants are ETERNAL. He is ALWAYS faithful, He always holds His side, even if we stray - abd if we do, He wants us to return.
Thus, a further problem with replacement theology - you would have to throw out the entire Old Testament. Yet the Old Testament points to the New Testament, Jesus Christ.
Since no replacement theologian whom I know of is calling for the abandonment of the OT, your conclusion seems quite suspect. What in replacement theology would require that? Allowing our understanding of the OT to be shaped by the NT writers is certainly not an abandonment of the OT. The author of the book of Hebrews provides commentary on the Jeremiah passage that you quoted in Hebrews 8, although not your exact verse, and is perfectly consistent with replacement theology that God the Father is dealing with mankind differently than in the past.
In response to a couple of other posts, let me add this. While anti-Semites might latch on to replacement theology, not all (or even most) replacement theologians or people who hold to the theology are anti-Semite.