no_vase, wow, thanks for the market update and your intimate knowledge on real estate finance, but the question was, "what's left to be invented?"
I suggested pre-fab which, yes i agree is currently the PC term for trailer park, but like it or not this is the future. Some of these SFR's in the OC can be considered partifally pre fab as trusses are completely manufacutred off site. Ikea, has started their own line of pre-fab, and whatever you think about the design, these buildings,when the tech is right and the volume goes up, will be much much cheaper.
High density isn't only built due to land cost, for one, there's zoning code, and for another, there market niche, some people want condos because they are cheaper. Very simplified reasoning would be that an $800K house is would move slower than two $400K houses on the same lot. Extreme case would be the high rise with $200K units that are like 200 sq ft.
In so cal, new home construction is already practically leed certified due to the state regulations, there's just the additional reporting, paperwork and plancheck that makes certification a headache. I don't know what blks problem is with the recycling process as it's a non factor, the bigger more expensive problems tend to be with energy efficeny and runoff. Anywyas, green is potentially a marketing tool (i don't buy that theory), but as time progresses, could effectively lower upkeep costs and promote healthier lifestyles (big maybe) which could factor into the homeowner upgrade from a power book to that ultra thin mac laptop.
That's gotta be the stupidest analogy ever, i feel dumber for having read it. Thanks.