You Gentiles are like branches of a wild olive tree that were made to be part of a cultivated olive tree. You have taken the place of some branches that were cut away from it. And because of this, you enjoy the blessings that come from being part of that cultivated tree.
After all, it wasn't natural for branches to be cut from a wild olive tree and to be made part of a cultivated olive tree. So it is much more likely that God will join the natural branches back to the cultivated olive tree.