Well, that's more or less what happened with Detroit after the riots. With the election of Coleman A. Young, the city essentially became a black city. The whites left for the suburbs. When the Arabs came in the 1980s, the blacks chased them out to the 'burbs, too.

It had to become nearly totally depopulated, and elect the first white mayor in 50 years, to start becoming a human city again.

Too bad, it would have been better off rewilded.