We could also just not live in San Francisco. That's a better option for many.
So maybe not everyone who wants to live there gets to.
Again, not from out that familiar with the area so maybe I’m off the mark here.
So instead of SF continuing to expand to engulf all of California, other cities in other areas would begin to grow. Somewhat this has happened - Redmond near Seattle, etc, but we haven't really had any "ground up" new cities that I can recall, they're all offshoots/suburbs of existing ones.