The disappointing answer to the book's title: still workin' on it.
But since I started reading the book a few days ago, I've kept my eye peeled for news. And it's pretty easy to find. A couple weeks ago, there was a Christopher Mims column in the WSJ: The Biggest Problem With Flying Cars Is on the Ground. (I.e., where are they going to land?)
But perhaps more sobering, from Reason's wonderful Katherine Mangu-Ward: Where's My Damn Flying Car?: An Update
Terrafugia, Inc., an MIT-born firm, has released a flight simulator for their model, the Transition. They're calling it a "roadable aircraft" because of niggling little details like the fact that you need a pilot's license to operate the vehicle. But it's a flying car. You can drive it to the airport, unfold the wings, and take off.
Only problem: that's from 2006. Terrafugia was taking deposits for delivery of the Transition in 2009. And you may have noticed: it didn't happen.
These days, Terrafugia has more modest goals: the SEEKER, "an innovative, electric, fixed-wing/VTOL hybrid aircraft designed explicitly for autonomous commercial aerial applications." Unmanned. Ho hum.
But back to the book: flying cars are only one of the areas the author, J. Storrs Hall, investigates. He's willing to believe they could happen, and considers a lot of the obvious constraints and objections: yes, flying is well within the capabilities of normal humans; yes, it's plausible there would be a robust demand for them; yes, there are no obvious technical gotchas. The big roadblocks are government over-regulation and the explosion of liability lawsuits.
But flying cars are only one example of a general problem. The concept behind nanotech was (essentially) thought up by Richard Feynman in 1959. K. Eric Drexler's 1986 book Engines of Creation (yes, I read it) told us all of the wonders just about to come… and then, meh. What happened? Hall has explanations there, too. Again, there don't seem to be any technical roadblocks, just misdirected government funding to organizations that don't seem very interested in doing anything revolutionary.
The book contains many other interesting technological wonders that could be ours, if only we'd get our act together. Some are (near-literally) blue sky. Worried about climate change? Hall doesn't mention my favorite solution, Artificial photosynthesis; instead he imagines billions of centimeter-sized diamond baloons filled with hydrogen, floating 20 miles up. They would contain mirrors that could be continually adjusted to reflect sunlight back into space: essentially a global thermostat. Cool! (Literally.)
Hall's stories are plausible and interesting. (He has an unfortunate hangup about the Copenhagen interpretation of quantum mechanics, though.) And his observations sometimes overlap into mine: he likes the technologically-optimistic SF of Heinlein over the pessimistic drug-inspired dystopias of Philip K. Dick. (My own: Dick has 46 writing credits at IMDB; Heinlein has a mere 20. And a slew of those 20 are from the execrable Starship Troopers franchise.)
All in all, the book made me think about Deirdre McCloskey's insight: that the "Great Enrichment" of the past couple centuries was due to a shift in beliefs and moral norms that extended respect and dignity to commercial activity.
I can't help but wonder if what Hall calls the "Great Stagnation" is due to a similar shift in attitudes. And whether such a shift will turn into a "Great Impoverishment". It's unfortunately not implausible.