To address your edit, it is possible and perfectly reasonable for prices to be dropping in San Francisco, while still having a massive shortfall of housing unit

To address your edit, it is possible and perfectly reasonable for prices to be dropping in San Francisco, while still having a massive shortfall of housing units and prices to be skyrocketing elsewhere. Prices will continue to go up significantly in places that are deemed desirable to live in until the prices are so high as to deter enough demand, then price growth should stabilize somewhat or recede if the market overshot. When will this end? When there are enough houses to house people in the places they want to be housed.