That is pretty much just building the shell. You mentioned land but you also have to throw in utilities hookups, plumbing, electrical, HVAC, floors, etc. A stick frame shell isn’t much more than $10,000 on a rental sized place, anyway. If there is a disruptive system it will probably be in pre built panels that include a lot of wiring and plumbing and can be shipped flat pack. Generally these type methods save on labor but are beefier designs so the materials eats up savings. So it’d be pretty hard to drop new home prices significantly faster than the rate of deflation (which would be the result of a positive supply shock like the one you are suggesting with comprehensive Automation).