Not the original commenter but, from past articles I've read the most effective way to create affordable housing is to let developers build new luxury housing.

Not the original commenter but, from past articles I've read the most effective way to create affordable housing is to let developers build new luxury housing. That has the ripple effect of directing the old luxury housing to become more affordable, since it's no longer the new thing. Unfortunately, the economics of building new housing on extremely expensive real estate, targeting an "affordable" price point just don't incentivize as much construction as the city needs.