SoCal is one big Burb for the most part.
I think it is every environmentalist dream that the remaining people in the world, move to high density cities, and impose some constraint on population growth as well.

But I don’t see that happening at least not in SoCal. Also cities once they become very dense are their own worst enemy as if you really do need to grow a business it is very hard to scale in crowed expensive cities. Telecommuting is not just for work anymore as well, more and more schooling is being be done via telecommute as well.

Gas will be less an issue with 100MPG and Nat-Gas cars (which are coming), someday there may even be some convent mass transit who knows. Look around, every time the city or utility needs to replace a Truck or car, it usually is with a Nat Gas vehicle these days.

As the economy improves the burbs will get back to cost to build+5-20% or so fairly quickly.
With inflation eventually the price will get back to peak nominal price, but that will probably be a while yet.