This happens where I work now, and only one person I know has done the Jump-ship thing and moved to a rural area.
It's easy to say "move to the bay, get a job with Facebook, move out" but getting a job with Facebook isn't easy, and moving is a ton of work. It's kinda like a problem that I really don't think would exist on a large scale. If the employee is worth X in the big city, they're worth X in the small city too, unless they were a shitty employee to begin with. In the end, the right people make the company, and if you're going to quibble over 10k of their salary, they should probably go somewhere else.
It's easy to say "move to the bay, get a job with Facebook, move out" but getting a job with Facebook isn't easy, and moving is a ton of work. It's kinda like a problem that I really don't think would exist on a large scale. If the employee is worth X in the big city, they're worth X in the small city too, unless they were a shitty employee to begin with. In the end, the right people make the company, and if you're going to quibble over 10k of their salary, they should probably go somewhere else.