So for one there is no such thing as "infinite demand". We can talk about Seattle having an unmeetable housing demand when the whole city is hundred story condo

So for one there is no such thing as "infinite demand". We can talk about Seattle having an unmeetable housing demand when the whole city is hundred story condo buildings and the population density is twice that of Tokyo. Of course in the short term, wherever you lift the crippling shroud of insane zoning policy, new housing will still be very expensive. It is pent up demand. But by building density you exhaust said demand. And on top of that, the denser and larger you build, the most scale you apply, the cheaper it gets per unit to house people. Economies of scale plus a bunch of other scaling effects on construction. One thing the first bastions of reasonable zoning policy will probably fail to do, though, is remove some fairly insane mandatory minimum square footage requirements, which puts a kink in any reasonable approach to housing - developers need profit, and the smaller you can make units the larger your market can be because you can fit more people into the same building footprint and thus afford to charge less per unit, and thus enabling poorer people to live there. Without that you do just end up with the luxury 2000 sqft condos that are only better than the status quo because they reduce pollution and traffic. They also dramatically help the local economy by enabling high income earners to live there in greater numbers. But to actually help the poor, you need to unrestrict not just the outside building size but the inside as well.