Most tech companies are allowing company-wide WFH for the rest of the year and in come cases permanently. That's tens of thousands of people who can be elsewhere for at least 6 months and possibly forever.
That seems like a change in the "physics" of the magnetism that has drawn people to SF and the bay area for decades. A lot of people who had to stay in the area due to work but who have been considering a move are taking the opportunity to relocate to places with lower cost of living.
Add that to the thousands of layoffs at startups over the last few months (and a presumed hiring slowdown), as well as thousands of H1B holders who are reassessing life choices. There could be a serious shift in housing supply and demand in the bay area. Oh let's also not forget the huge impact the pandemic is having on the service and hospitality industries.
I think we could see a long-term reversal of the trend of 15% annual rent increase in SF.