At some level I can accept the contention that "something's gotta give," if for no other reason than American productivity will not likely remain relatively as high as it is compared to the rest of the world forever. But I absolutely reject the notion that the change will be some catastrophic fall into the abyss. This is going to happen over time -- a relatively long time. Gas prices will spike and fall now and then, but the end of "cheap oil" will not be akin to "shutting off the tap." There are too many sources of oil available to us that are not in play today, but would be if prices stayed high for the long term. Some of them were starting to look attractive at $4 per gallon gasoline, but not quite. That presents, however, an upper bound on gas prices in the short term, which I define as the next hundred years or so. I also reject the contention that technology cannot get us out of this. To the extent that we remain fundamentally so rich as an economy, technology will continue to bail us out. That's the funny thing about technology -- no one predicts the next big breakthrough. I won't bore you with the quotes of patent officers and their statements to the effect that everything's already been thought of. What will bring us down, however, is that at some point we may not be able to afford the technology because we have slipped in our standing as world leader in output. I don't see that in the next several generations, by the way, but we're still a relatively young country. If we can rise as fast as we have, then others can do the same under the right circumstances.
In the end, Kunstler comes across as little more than so many naysayers who have fallen by the wayside unvindicated in the past, though I do agree with his thesis about communities. When times get tough, having connections with the people around you makes a big difference. And to the extent that suburban sprawl and McMansions hinder that (if only psychologically) then I can at least be on board with that.
By the way, if I were to look for the excesses in our country that will need to change the most (especially since this thread at least partially addresses housing) is the notion that families must have homes that are as big as what we are accustomed to here. Look around the world (or even into the really poor areas here) -- at some point we will not expect thousands of square feet of housing for each family. The impacts on energy use of THAT change will be much more profound than cutting back on cars.