Correct. Christ is the fulfillment of all the ancient prophecies, not their replacement. The technical term is typology.
Christianity is the New Covenant. But it does not replace and vacate the Old Covenant of Israel, it fulfills it. There are several place in the Bible where God tells Israel words to the effect that “My Covenant with you is forever.” The Jews may fall away and betray the Covenant, but God has promised that he will never abandon them. St. Paul (I forget exactly where) also declares that the Covenant is forever, although of course he converted, himself.
This does not mean that God does not welcome Jews into the Christian faith. But it does apparently mean that at least some Jews will remain, and will one day return from Exile and be welcomed back once more as God’s Chosen People.
Christianity is the New Covenant.
The new covenant is the covenant with Abraham, come to full fruition.
The old covenant is Sinai. Law. Do this and live. "All this we will do" for the next 5 minutes.