Harvard scientist Robert Putnam found that diversity hurts civic life, reduces social trust, pushes tribalism / grouping when the minorities are large enough to form their own enclaves.
Too much diversity, and you get balkanization.
Yes. I must read about Robert Putnam. People will self segregate to live in groups most closely reflecting their own minority. Even if they live in a diverse neighborhood, they will socialize with their own ethnic group if they can.
It seems in my life dooing cooperative work and going to college and regarding highly other productive people of different ethnic/racial backgrounds was for me a mind broadening experience.