I think there's far too much wiggle room in the analysis of land-value vs improvement and would strongly prefer a solution that moves away from perpetual ownership and towards revolving leases instead. The way to do this non-coercively would be to gate the enormous tax benefits we bestow to real estate windfalls (1031 exchanges, the $500k exclusion, the 15% and 20% capital gains rates) behind conversion to a 99 year lease. We won't see the shade beneath those trees but our grandkids will.