Explain to me how you get Saratoga, Cupertino, Atherton, etc to conform to Y. And why should they?

You get them to conform by passing laws at the state level to take power away from the local residents. I know they wont comply, we have already seen the problems that giving local control creates in this scenario, so the solution is to make a decision for the larger and long term good.

No, you have multimillionaires that won't sell and will fight change.

Well sure they will fight, but thats not a good enough reason to not do something. Hopefully the state government has enough political capital to deal with the fight that the relatively small population of homeowners will put up.

Because if Atherton doesn't build housing, Oaklanders will burn down Atherton for exporting the problem eastward as gentrification.