The demise of the oil based economy does not depend on the specific conclusions of the peak oil theorists. The demand for oil is skyrocketing world wide.
Some people may think that new oil is being made every day. Personally, I don't. Most of the oil fields in Texas are nearing exhaustion. For some reason, nature has decided not to replace the oil we removed from those fields.
But irrespective, unless the world is making several million barrels every day, and putting it where we can get it, then the supply of available oil is going down. You can poo-poo it, but the fact is that it's oil that makes our economy go. Without it, we'd starve. And everytime the price goes up, our economic welfare goes down.
In general, the price is going up, not down. Even in the 90's, when oil was at about $15 a barrel, it was pretty clear that it was going to have to go up. Oil companies were losing their shirts. It was not sustainable. Now, it's sustainable for a while, but only at much greater cost.
There is a lot of oil in the world, but we are using it at a break-neck pace, and with globalization, it's a mistake to assume that there are vast new areas of exploration that we have not already tapped.
This is incorrect. The demand for Energy is skyrocketing world wide. It just happens that currently crude oil is the cheapest, most efficient form available.
I've seen estimates for the tar sands region of northern Alberta suggesting that the oil from that source could sustain current consumption levels in all of North America for more than 500 years. It may not be feasible to get most of it now, but in an age when technology improves in leaps and bounds over short periods of time, I'd say there's a good chance we'll eventually use almost all of it.