Why doesn't Google or Facebook just pack up one day and go to... say, Detroit? Buy a shitload of property there, and tell all their workers that in the course of the next 5 years they want to have presence in two places: this new place in Detroit, and the old place in the Valley. Whoever wants to stay in the valley can stay... and whoever wants to move to Detroit can come move to Detroit. Same pay.
It would win a lot of good will... and it makes sense. The engineers making $150k will actually live what living on $150k is supposed to feel like. It'll jumpstart the hell out of Detroit... etc. etc. Not necessarily Detroit (I just chose to say Detroit because property there is so much down the shit that you can buy a sizable portion of the city for a good few million).