Broadly, there's enough space in the Peninsula to build whole high-density self-contained cities - Facebook wants to build housing at their office park and if the only condition was shops in walking distance too, I'm sure they could satisfy that requirement also.

Maybe these possibilities haven't been explained well but I sort of think there are other interests that would prefer things stay approximately as they are.

Edit: one aspect that occurs to me is that developers probably wouldn't want a process that solves the housing crisis immediately either. It seems to me that satisfying the pent-up demand for housing gradually, project by project, would allow a developer to scoop up a lot of the excess, monopoly home-value now enjoyed by homeowners whereas if a huge stock of apartments appeared in one big bang, developers could wind-up selling them at costs plus a small profit level.