None! God does establish the new covenant with the house of Israel and Judah. Scripture is clear and consistent on this in both the old and new testaments.
Pauls words in Ephesians and Romans shows that he believed that gentiles become part of Israel, not physical Israel, but the Israel of God, and become partakers of those promises given to Israel.
If we're Christians we're under the new covenant and we now have hope and God in our lives...as Paul said.