I live in a neighborhood in Manhattan where the opposite is happening (I have slowly watched my neighborhood become whiter). Do they call that brown flight?  Humans are naturally drawn to their own 'kind', but humans are not breeds of dogs, they have more complex ways of choosing those who share their same ethos and interests than 'you have spots, I don't'.  I went to a diverse university, and as much as there were segregated tables, there were unsegregrated ones. Luckily I found the latter. I wish there were such simplistic rules that dictated human behavior/preference in all circumstances. They call it gentrification and it's great :D