If Google thinks this will be an issue dealing with Mountain View, they'll just go with a whole new location. This isn't brinksmanship.
You might be surprised to hear that a significant number of Google employees in Mountain View were recently moved to a new campus outside of the city, and it wasn't exactly an opt-in affair.
No one is so beholden to their almost indistinguishable south bay suburb that they wouldn't venture across the border to go to work -- these towns are 20 square miles at best.
That would be pretty sweet if a giant tech company like Google packed up and left Silicon Valley. It's going to take big moves like that to get a real exodus rolling.