Yep, tech companies go where the talent is, and there's a lot of talent in the Bay Area and there will be for a long time. But it's an outdated belief that the Bay Area is the only option out there. There are a ton of great cities with lower cost of living, less traffic, better schools, and less crime across the US. Places with a decent climate (albeit not as mild), access to the great outdoors, terrific restaurants, farmers markets, and so on. Even before the pandemic tech was moving jobs and operations to other locations, very often quietly. Austin, Denver, and Reno come to mind.
There was no "mass exodus" out of California, but the pandemic accelerated an existing trend of people leaving the state -- did we already forget that CA lost a seat in the US House of Representatives? And as should be expected, some people are moving back to SF after escaping to some exotic (to them) location for a year while the city was locked down. But I don't expect they'll all come rushing back. In the meantime, Silicon Valley still has the long-simmering problem that a majority of residents are dissatisfied and looking elsewhere.