SF is great (really, just stop it haters!) and there will always be people who want to live there and prices will always be
relatively high.
However, for a long time SF has been a place of extreme price distortion because of low (~no) new construction and huge concentration of high paying jobs. The result is many many people feeling trapped there way beyond where it makes sense for their lives. If you are single and living with roommates, making $200K at Twitter, then great! SF is awesome! But when you have two little kids, and/or you just aren't making that much, in a place where small houses are > $2M things are very different. That's me BTW. We hung on for 6 years after having kids and in that time almost all couples with kids we were friends with left. The people we knew who stayed were either much wealthier (had nice exit from previous company) or were really trapped and talked constantly about leaving.
So honestly it does make sense to me. Somewhat anecdotally, I personally know about 15 people who have left since April (including me, SLC is freaking awesome!). For comparison, I personally know exactly 2 people who've had covid. So yeah lots of people really are leaving and the closed bars are just a small factor (IMO), being able to finally move is the much bigger change driving this migration.
I don't think SF will die but rents and home prices coming back down to earth will be a very good thing for the city (my landlord bought the building in 1981 and was charging us $4K/mo for our 900sqft 2br flat, I won't feel bad for him if that deflates to $2500/mo where it should be). The ultra high prices have slowly gutted large parts of the city of anyone but the young or wealthy, mostly tech people. Maybe in a few years SF will be more affordable and consequently a much more diverse city again. That would be great IMO.