Before we turn this thread into a flame war, let me try to intervene.
I threw out the 30 year figure as the time between now and the end of industrial civilization. Between now and then, the Middle Class will disappear. Globalization will disappear. The NYSE, Federal Reserve, US Federal Government, European Union, United Nations, and thousands of other organization created out of a "need" for increased Bureaucracy. In 30 years time, Wal*Mart will be gone, Home Depot will vanish, and the local supermarket will no longer have fresh pears in January (unless you live in Panama, but then, it doesn't really matter). Suburbia is on its way out right now...(in theory).
You're right, the limiting factor is energy. Long commutes will go out of fashion and people will attempt to sell their SUVs and buy smaller cars. A series of recessions will cut down oil demand for a long period of time. Lots of people will be out of work and many will lose their homes. However, the government won't allow them to die off in large numbers. There will be some sort of Soup Kitchen "solution". Jobs once done by machines will be done by people. But this only gets you so far...
Pretty soon the laws of deminishing return kick in. Efficiency peaks and the average standard of living drops below the povery line. That's when chaos breaks out. The Government will go completely broke and we will have to learn how to care for ourselves. I don't know how this plays out or how long it will take. At max, 30 years. But it could be as little as 10.
http://www.wolfatthedoor.org.uk/ predicts this and I think it's fairly reasonable:
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')Rise in oil prices bring on recession in North America and Europe. Blamed on OPEC.
Food and power shortages hit Asian and African countries but is largely ignored in the Developed World as "this is what is expected over there".
Major dispute between Canada and USA as people of the former wonder why they should have to freeze so that their natural gas can keep the people of the latter warm (or cool, as the case may be).
Yet another 'discovery' of the enormous resource in tar sands. Yet another attempt to explain why it isn't the same as conventional oil.
Oil depletion causes aviation fuel to soar in price. Distant tourist areas such as Pacific islands, South Africa and Australia/New Zealand notice massive drops in visitors which result in rises in unemployment.
Oil shortages in China force it to resort to coal to produce electricity. Acid rain and other pollutions spread across Korea and Japan.
Blackouts and brownouts hit the USA and Europe. Blamed on privatisation / effects of global warming / recession / aliens.
Exotic foods in shops begin to rise in price and become less common. There is a new fad for turning parts of your garden aside for growing vegetables. Endless TV shows about gardening.
In the home, there is a rise in energy-saving measures such as small solar heating panels, lightbulbs, insulation. Endless TV shows about DIY.
Rise of interest in small cars and motorcycles (anything rather than public transport). Four wheel drive vehicles become even more embarrassing to own and are given away free with breakfast cereals.
War breaks out between Vietnam and the Philippines over oil in the South China Sea.
Worldwide reductions in crop yields. Costs of food soar. Millions starve or suffer from malnutrition. Global economies devastated by need to feed their populations. Revolutions spread across South America and Africa. Banking system in collapse.
OPEC restricts supplies of oil to USA, already suffering massive losses of hydrocarbon supplies.
Third World War begins..