What's happening is that the word is getting out to the engineers: SV is too expensive a place to be, even at GoogleMicroUberAmazon pay rates. The gold rush is over.
Sample size of one, but this is true for me. I'd really like to come back to CA, but I make 6 figures already, and a 3600 sq ft house is only like $400k here. I don't see what SV has to offer except a larger market for opportunities, but I'm in my mid-30's, so I'm worried that I'm not really a target demographic for SV employers.
Microsoft and Amazon, not so much, to say nothing of the majority of other tech companies that aren't well known as the top paying three companies out here.
Nobody wants to work for a startup in Gilroy...
I was just using Skype as an eponym.