Of course, the trouble with the model proposed above, lots of smallish, quasi-independent communities, well-organised to facilitate sustainability and with minimised dependence on any wider infrastructure, is that they have an inside and an outside.
Inside, all is reasonably well. Outside, especially in the immediate environment, all had better be approximately as well also, or you can predict attempts at expropriation, either direct, e.g. theft, or via government facilitated corporate expropriation of some kind.
On a global scale, we're back to the population problem. We have about 6 billion people right now with numbers increasing fast, especially where no social safety net exists, i.e. in most developing countries. The most plausible looking sustainability calculations I'm familiar with, say that the planet could support around 1-2 Billion with roughly an 'EU-normal' standard of living, but based on some form of sustainability organisation like that described above, or rather less than 1 Billion living an american-standard way of life, if this could indeed exist at all sustainably.
Any larger sustainable population number, tends to make some pretty nasty looking assumptions about living standards. Above 2 Billion, you start having real problems in simultaneously growing food and generating enough energy sustainably, because you're running out of land for crops you can turn into ethanol or to set up photovoltaics sites etc. Here are some sample numbers from
Pimentel The calculations to arrive at these numbers are available in Pimentels academic papers and I'll dig out links if anyone really wants to read them.
"Assuming that 0.5 hectare per capita is necessary for an adequate food supply, and assuming that soil conservation programs were implemented to counteract erosion, it would be possible to sustain a global population of approximately 3 billion.
Alternatively, with a self-sustaining renewable energy system producing 200 quads of energy per year and providing each person with 5000 liters (1300 gallons) of oil-equivalents per year (half the current US consumption, but an increase for most people in the world), a population of 1-2 billion could be supported in relative prosperity. This adjustment could be made over a century or more."
So, while the ruralisation model described above tells how a minimum of 1-2 billion (and maybe a few more if you really went for it instead of mucking about with half-measures) people could survive in reasonable comfort, given some major social changes, it has nothing to say about what's happening to the remainder.
Nor does this model have much to say about what corporations and all their pet governments are doing while this is happening.
Achieving sustainability at around the 2 billion mark, involves taking a whole bunch of energy-sucking and fundamentally unsustainable steps out of our food chain, but these are key steps from the point of view of various major corporations profits. Sure, anyone selling windmills is fine, but petrochemical and pharmaceutical companies, supermarket chains, industrial food processing companies et al, all stand to lose out big-time here.
My prediction therefore, is that they'd work to protect their profits at all costs. They aren't measuring their performance against anything to do with sustainability, the capitalist model forces them to optimise for profitability and maye also growth, and they will thus tend to use every tool at their command, especially their governments, to prevent their profits on our food disappearing.
Also, it makes a real difference which country you start off in. The US is in relatively good shape in terms of hectares per human and natural resources. The UK is in rather worse shape and many developing countries are in far worse shape, for instance China.
