Would all of the descendants of people who had not already lived here, say, 10,000 years ago, have to leave? If not, why not?
The only people required to leave will be white people. Once they (and their statues) are gone, Hofstra and America will be able to live up to their real potential. It has been tried before with amazing results. Rhodesia/Zimbabwe for example.
Not true. History tells us that empires, nations and tribes generally desire hegemony - regardless of skin color.
At its apex, the ancient Egypt empire stretched from modern-day Syria in the north to modern-day Sudan in the south and from the region of Jordan in the east to Libya in the west.
The biggest land empire that history witnessed was that of the Mongol empire. The Mongolian empire extended from the Yellow Sea in eastern Asia to the borders of the Eastern Europe. There were several time when even China, Korea, Mongolia, Persia (now Iran), Turkestan, and Armenia were included in the Mongol empire. Also parts of Burma, Vietnam, Thailand, and Russia were included in this vast empire.
At its height the Ottoman empire encompassed most of southeastern Europe to the gates of Vienna, including present-day Hungary, the Balkan region, Greece, and parts of Ukraine; portions of the Middle East now occupied by Iraq, Syria, Israel, and Egypt; North Africa as far west as Algeria; and large parts of the Arabian Peninsula.
No one would characterize these empires as being led and dominated by Europeans.