NYC has plenty of problems, don't get me wrong, but I'd argue Brooklyn actually has a pretty straightforward model for this that would apply to San Francisco.

The general idea is figure out which areas have a core aesthetic that defines the area and is worth preserving, and landmark them. Then take the stuff that isn't in that category and basically let people go nuts with it and build high rise housing, and have some clear incentives for affordable housing that get it built into major projects.

Meanwhile make sure to take care of the parks and the waterfront, actually have real transit, and don't give a shit about humoring people who insist on driving.

Try it.