After all, teleconferencing all the time is not the only alternative to everyone living in the same city. People could actually travel for important meetings from time to time.
A best-of-the-class high-speed train (300mph+, not the pathetic 200mph version they're talking about) should be able to get you from Portland to SF, or from LA to SF, in two hours flat. Even better, you'll be able to work during those two hours.
And then they could uproot their workforces (and if you took the combined employees of Yahoo, MS, Google, Apple, AOL, Facebook, etc, you would have moved the employee base) and move there, it would probably be the most futuristic city on the planet.
I mean, they wouldn't - or they already would have - because it isn't economically feasible. But that always comes off as a buzz kill since we just end up trying to grow new businesses like cancer into the ancient ruins of lost revolutions we call "historical preservation".
The biggest thing preventing tech workers from moving is that some interactions simply must be done in-person. Often this requirement is due to culture, not technological limitations. Still, there are significant advantages to in-person interactions. People are much more likely to pay attention to each other. There can be interesting and beneficial chance encounters. And of course, the likelihood of anything getting recorded or leaked is lower.
I think that as remote work becomes more feasible (both technologically and culturally), more tech workers will move out of the bay area. There are simply too many incentives to leave.
1. The worst being Guam, which couldn't keep electricity running for more than 12 hours a day. Great beaches, though.
2. Oh, and who had the bright idea to put cloth seats on BART? That person has probably caused the spread of more disease than Typhoid Mary.