Mandating some percent of units be "affordable" or charging various taxes which go towards building affordable is not unprecedented. But those strategies succeeding might be. ;)
Kinda hard to tell, since they only allow a few new residential buildings to go up each year. If they didn't allow NIMBY interests to prevent _any_ housing from going up, we might actually see this in action and be able to tell.
This was done in Toronto when I lived there in the 90s. And it appears to have been successful. Society benefits in many ways (including saving money) by not having poor people live in slums.
Like thedufer says, as soon as the real blockers to development get the fuck out of the way, we'll see how well Rent Stabilization and the "Affordable Housing" mandates work in SF.
As it stands now, it's next to impossible to build in the city.
Frankly, subsidized housing succeeds in many districts. Once SF and -more generally- the SFBA decide to stop lining the pockets of real estate speculators and investment firms and start building housing to meet the current and future demand, we'll see a change in the character of the area for the better.
Mandating some percent of units be "affordable" or charging various taxes which go towards building affordable is not unprecedented. But those strategies succeeding might be. ;)