The land grant was fulfilled, their tenure their was dependent on obedience. It was a typoligical recapitulation of Adam in the Garden, and the purpose was to ahow that "the just shall live by faith [of Abraham]." Paul tells us that all the promises [to Abraham] are fulfilled in Christ, and that the inheritance (for the meek, one might say) is the whole earth--and it always was.

Romans 4:13 KJV — For the promise, that he should be the heir of the world, was not to Abraham, or to his seed, through the law, but through the righteousness of faith.