When you are old your values change and you're just looking for convenience and people in the same boat. That does not mean they want to not have ethnic diversity they just don't want to deal with non 'generians so much. They still want some younger people, but want the understanding of older people around them --no, they also don't want to be depressed by those near the end, but I'm not talking that stage home.
And I don't think homogeneity is gross. Do you think Nigerians feel gross, or do you think the Japanese feel gross? It's neither better nor worse then heterogeneity.
Gross. I get that some people get to places in their lives where they don't want to deal with diversity, but I don't want cities to turn into places like that. Retirees (those who do want to stay, and don't want to live in a retirement community) are a part of that diversity. Shipping anyone off involuntarily (or even semi-involuntarily, in the case of ridiculous housing cost swings) is completely unacceptable to me.