The question used to be pretty simple: "has a sufficient portion of the market been priced out to the extent that demand collapses"?
As we've seen in equities / derivatives (and increasingly, commodity) markets - the answer to that question is now perpetually "lol, number go up" because large investment banks have essentially infinite access to free money and will be bailed out if they get in trouble.
On a long enough timeline the end result of this is that more and more Americans write their rent checks to institutional investors. [1]
Sure, many Americans own their homes now (or have a nice cushion of equity). But what happens as wage growth continues to stay relatively flat while cost of living rises dramatically and folks need money for medical bills or their kid's college tuition (or w/e)? They sell and become renters.
There's a pretty bleak future for American housing absent regulation in this space.
[1] - https://www.theatlantic.com/technology/archive/2019/02/singl...