The problem with "Peak Oil" theories is the fact that they conveniently ignore the fact that as the price per barrel goes up, the amount of oil that can be profitably extracted & refined increases.
Oil shale can be profitably processed into "regular" oil for $70-100/barrel. Known reserves of oil shale estimate that there's enough of it to produce at least 2-3 times the oil as known reserves of conventional oil... and most of THAT is in the United States.
Wait, it gets better. The main reason the bulk of it is in the US is because the US, Brazil, and Russia have been the only places where people have actually LOOKED for it. There's increasing evidence that China has at least as much shale as the US.
The main reason why nobody bothers with shale right now is because it's only profitable at prices of $79-100/barrel. If the market price of oil falls below it, the oil companies lose money on every barrel they produce... so they aren't going to spend significant amounts of money investing in it until they're convinced that the market price will never, ever fall below that level again.
My favorite analogy is "Peak Wood". It occurred in urban Europe during the late 1700s, and urban America in the late 1800s. Prior to that time, wood was so abundant, people didn't even bother to worry about farming it... they just went out, found trees nobody cared about, and cut them down. Or paid someone to do it for them. As cities grew, unclaimed wood became harder to find, and people started to farm it as a cash crop. Eventually, even THAT wood became too expensive to burn, so city dwellers switched to coal.
Hundreds of years after "Peak Wood", we still buy furniture and flooring made from wood. We even still burn it in fireplaces. The difference is that now, we buy shrinkwrapped quarter-logs for $5/ea to burn on Christmas for ambiance, and heat homes with things like natural gas, oil, and electricity. Most furniture is made from plasticized sawdust, with either a picture of wood or a thin layer of wood glued to the outside where you can see it.
Of course, we can't forget the most important use of all for wood today: toilet paper.