its pretty sector dependent. if you're just building a generic SaaS or consumer product, you'll probably be fine in a lot of other cities. if you're in AI, SF is essentially the epicenter for that
There is still an insanely high concentration of tech workers so there's a very high chance your neighbors, friends, etc are in tech. in the south bay it feels like everyone works at FAANG/Cisco/Intel/Adobe etc, you get the point.
basically you no longer have to be here to build cool stuff outside of like AI, but your highest chances of success in either the startup world or the corporate ladder are still here. if you can't make it in tech/find your groove here, it'll be on you. the vast majority of innovation, now that crypto/miami are forgone memes, will still take place here in the near future
considering state politics and high housing prices, who knows if that'll last? maybe it makes a huge comeback like nyc (it was in a much worse state in the 70s/80s). maybe it goes the way of detroit. the answer is probably somewhere in the middle