Using history as a guide, about 60 years or so. Always happens leading up to the crash-and-burn phase of a generational cycle (saeculum), which is about 80 years. If you place the 'vernal equinox' of the last Kondratieff fall at 1930, then it's about right... We started the 'McMansion' phase in the 1990's. We're at the winter solstice right now. So-called 'K Winter'.
In the upcoming two decades, we're going to be doing what the 30's thru 50's modernists were doing - reinventing architecture... and mostly failing, with a few brilliant exceptions.
Now where's my deflation? Bring it on.
