> right now the major metros have a lot of pent up demand

The major metros have the least to worry about from this. Those cities have high housing costs because of demand, or to put it another way, those cities have high demand despite high housing costs, and the economic factors that cause people to be attracted to cities aren't going to go away; density is devastatingly efficient and it's cheaper and more convenient for people to be close to things. But what this means is that as the population falls, that latent demand causes the less dense, lower-priced areas to depopulate. See Japan's crisis of rural depopulation, and how Tokyo isn't the one feeling the pinch.