I don’t think that 6% – 8% growth is sustainable in the very long term to begin with. If that were the case, people wouldn’t be able to afford houses anymore since housing would consume a bigger and bigger proportion of income.

I think that Schiller researched housing prices at the peak a the end of the 19th Century. Prices peaked and dropped but did not recover until after WWII (if I remember well).

It’s not beyond reason for house prices to stagnate for a very long time. If China and foreign economies grow faster than ours, then that scenario is quite possible.