I'm old enough that I remember my home town (which has been inundated by California retirees) as having 100% family-owned grocery stores, drug/general/hardware stores, distributorships, all of which started shifting heavily to chain and corporate dominance by sometime in the late 1970's. Since the modern concept of retiree and tourism based economies hadn't taken hold, 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. The irony that a lifestyle of living in a nicer small town with a Powerwall and a Model 3 is both less sustainable and less diverse is not lost on me.