apologies for coming back to your post so late, I only now figured out that there is a list of answers to one's own posts when checking the MailBox.
I believe it is remote to ponder a 20 million potential supply/demand gap out to 2030-2040. The US continues to be an immigration country, 20 million additional people are getting into the country in a matter of a lot less time. Check this out, an increase of 20 million of the civilian noninstitutional population just between 1997 and 2003:
Real estate cycles appear to be shorter, maybe in the 5 to 8 years time range. I don't think such a huge supply/demand gap will ever develop but it should be more of a moving adjustment, and that adjustment customarily comes through prices. At this point in time I think it is very likely that the housing price increases of the last few years should slow down markedly. FWIW.