Well, there's a much easier alternative, which may be in reach now: rich people and tech workers become fed up with SF and leave in droves. Rents plunge and houses become much more affordable, and service workers can live there again.

This would require a level of fed-up-with-SF that I don't see in practice - like every other tech worker deciding to leave, and people in other industries too. But if that happened, yes: SF would become affordable and people with lower incomes could purchase houses there, and honestly that might not be such a bad outcome.

The city was once like this, after all - a place where people with low incomes, along with oddballs and misfits, could put down roots (buy houses) and live.