Kunstler, who would the own the title King of the Acerbic if Eric Alterman did not exist, feels that the future is in small towns and villages scattered about the landscape, each with enough resources to be mostly self sustaining. He would banish both the large towers, and suburbia, and replace it with a pastoral 19th century setting.
However, there is a strong counter argument that says that the bigger the city gets, the more efficient it becomes.
One mistake that some of the local source people make (not Kunstler so much) is that they confuse sustainability with efficiency. It may be very well more sustainable to have adequate sources of fruits and vegetables within your immediate local, and to have a supply of preserves stored up in your root cellar. But it is not more efficient. Efficiency is generally driven by specialization, and the size of city allows a lot of ultra-specialized people to cross communicate and work together with ease.
If you wish to maintain our current population, and the add ons as we get to the supposed leveling off plateau of 10.5 billion people, you need more mass production. If you are of the opinion (which Kunstler is) that none of it will last in any case, you may be willing to take your loses in exchange for a less drastic loss down the road: very similar to what is referred to as a safety play in the card game bridge.
... In city after city, the indicators of urban “metabolism,” like the number of gas stations or the total surface area of roads, showed that when a city doubles in size, it requires an increase in resources of only 85 percent.
This straightforward observation has some surprising implications. It suggests, for instance, that modern cities are the real centers of sustainability. According to the data, people who live in densely populated places require less heat in the winter and need fewer miles of asphalt per capita. (A recent analysis by economists at Harvard and U.C.L.A. demonstrated that the average Manhattanite emits 14,127 fewer pounds of carbon dioxide annually than someone living in the New York suburbs.) Small communities might look green, but they consume a disproportionate amount of everything. As a result, West argues, creating a more sustainable society will require our big cities to get even bigger. We need more megalopolises. Scaling Laws for Cities