Not the OP, but I actually think there's a chance greater density might, long term, increase housing costs in SF, though this is kind of an artifact of borders.

Not the OP, but I actually think there's a chance greater density might, long term, increase housing costs in SF, though this is kind of an artifact of borders. SF isn't taking full advantage of the business opportunity that greater housing density presents. It could be that more density, especially if handled well (better public transportation, proper infrastructure) would lead to even more economic activity, more high paying jobs, and so forth. Keep in mind, the cities that are more expensive than SF tend to be denser as well. People actually do like dense neighborhoods under the right circumstances - dense parts of Brooklyn and Manhattan are more expensive than SF, and some of SF's dense neighborhoods are more expensive than the low density ones (russian or nob hill vs excelsior or outer sunset). I figure that the desirability of higher density housing with good public transportation, combined by the increase in economic activity from greater density and a larger population... yeah, it could happen. Not saying it would, but I don't think it's all that outlandish a thesis. Also, this is partly a trick of borders, since lower cost housing would probably be built outside SF's proper, so taken as a region, costs could drop even thought they went up in SF. Kind of like Manhattan vs New York generally.