> If every major tech company in the Bay Area switched to remote work, allowing employees to work from anywhere they wanted to as long as they stayed on the same schedule as those who remained in the Bay Area offices, my guess is that there would be a large exodus.

Yes, but the problem is that many companies have found that remote work is significantly less efficient.

So if you need to cluster your work force somewhere, the Bay Area is probably where you'll have to given the desires of your top people to live there.