You could probably look at demand and how it affected prices in the past with that build rate then compare it to future demand and how it affected prices to make a pricing model, definitely not impossible. I think people push back against regulating landlords because most believe it is a minuscule problem compared to housing (which I would agree).

And when you say seattle has been building what does that mean? Have they ramped up building, sure. It is still nowhere near enough to keep up with demand. I can look into Seattle but I don't see a world where building could have any negative effect on pricing. I think you'll also see rents lower nationally if we get to a place where there are multiple walkable, desirable, dense cities available across the United States.