There was a promise and the promise stands.
The promise - i.e. the land of Israel being the physical birthright of the Jewish people - is a foretaste of the Kingdom, not the Kingdom itself.
The hope of the Apostles and the Fathers was not that they would one day have title to the land of Israel, but that they would have life everlasting in Heaven.
That is the covenant, and that covenant is accessible in only one way: the free grace of Jesus.