Anyone wanting to live in Nashville (just to pick one city from the list) who's capable of working for Amazon is also capable of working for someone in Nashville today. And generally, the economics of being tech talent outside these hotbed markets like SV and Seattle are vastly favorable.

That is to say, you're probably better off buying the cheap house in a smaller market on the salary you can command in that market than you are buying a very expensive house on the salary that the very expensive market offers you. Google would pay me more than my current job, but my cost of living would go up by more than my salary -- massively so.