Sure we do, across the world and in the US. Simon Kuznets provided the empirical 15-25 year waves. Doug, you remember the REIT crisis of the mid-1970s and the S&L crash of the late 1980s? (Worse in some places than others to be sure, but hard not to notice vast real estate overcapacity, mortgage defaults, negative equity and 30% price declines in key markets.) Same processes here in South Africa. Read Neil Smith's Uneven Development or David Harvey's The Urbanization of Capital and The Urban Experience, if you need the marxian theory of spatio-temporal uneven development which helps explain the way both amortization waves and gentrification trends affect the Kuznets cycle.