Many of us look down upon the Amish for avoiding the use of modern technologies (in fact they use more of it than we think, e.g., they use cell phones, albeit with many restrictions). But in fact, they might be well ahead of the rest of us. As I wrote on my page last year, one way or another we will go from post-industrialization to micro-industrialization once we either stop using fossil fuels, or they run out within the next 100 years. Alternative energies and muscle power simply will not be able to produce nearly the same energy levels that we rely on today.
Although this will be a difficult (catastrophic?) transition, humanity will likely adjust over the following 100 years, with a much larger proportion of people farming any remaining arable land.