Despite having significant growth opportunity San Fran is already twice as dense as Seattle. Therefore Seattle has room for explosive housing growth. It would need more changes than just housing of course. But that's to be expected and totally doable.
Cities are huge economic multipliers. We don't need more cities yet. The ones we have are perfectly great! We need to more efficiently use what we already have.
This housing crisis isn't affecting just "top tier" cities. It's not just New York and San Fran. It's Seattle. It's Denver, Austin, and Portland. It's even Nashville!
Every city, top to bottom, needs to be doing more. And they need to start now as the longer they wait the more expensive the infrastructure adjustments become.