Sadly upzoning those areas still won't be enough housing. And some areas (like piers along the Embarcadero) the neighbourhoods like Telegraph Hill viciously oppose them too.

I don't think the "neighbourhood character" test really holds much muster. Maybe if you bought one of the Painted Ladies, or are on a street that is 90%+ Victorians. Maybe.

I live on 18th and there are few Victorians left. There are a lot of ugly 60's and 70's 2/3/4 story buildings. These could all be upzoned to 6-8 stories without having much of an effect on "neighbourhood character".

My view is you don't buy a time capsule, you're buying a block of land in an evolving city. Things will change, they need to.