While some “-towns” exist for these reasons, others do not.
Consider “Japan-towns” and “Korea-towns”. You have people of various generations who go there, and you also have others who simply love the products and food of those cultures.
There are also factors to take into consider about where people choose to live.
You can find in some cities areas where people are of a similar ethnic background where they choose to shop for certain things, but not necessarily live — rather where they live is dependent on their income and self perception in the country in which they live.
You can maintain an ethnic self identity and still integrate with the rest of society that doesn’t share your ethnic identity — and it is easier to do if you don’t view the rest of society as “the other”.