> towns of that type had to be mostly independent in terms of income for money inflow....small factories, mining, farming and ranching, etc.

> I'd say that this movement of people who can afford it just another side effect of something bigger.

It sort of sounds like you answer your own question (/hypothesis): consolidation of industry. Which also seems to be a pretty big driver in wealth inequality. I've no idea what the correct response is here -- greater regulation to increase competition, so that there are more smaller players across any given industry? Who knows.