I think the biggest problem with it locally is it creates clear cut separations of the masses.
Neighborhoods are filled predominantly with the same race and promote future growth within their own culture. Opposed to integrating and coming together as a whole, people stick with what they're comftorable with.
I went to public school and I see this not being as big of a problem in the future. I had friends of all sorts of ethnicity and it didn't matter because if I spent time with them we had a common interest. It was when I met their older siblings or parents who had westernized their values that there were moments of discomfort.