Put the next conference in Las Vegas. To hell with SF.
It could happen. Apple pulled out of the annual MacWorld Expo a couple years ago, held at Moscone Center in SF. Attendence dropped real low after that. But I don't think Apple cares what SF thinks, they don't purchase that much from Apple. I used to manage a team responsible for networking there, and the majority of devices citywide were HP/Compaq and Dell. Incidentally, SF was wasteful and recycled very little, most stuff was just dumped in the trash - very non-green.