Very expensive oil is probably coming ... whether or not you agree with the peak oil theory, it is becoming clear that the days of finding huge, cheap to access reserves is probably behind us.
On the other hand, once the price of oil rises and stays beyond a certain point (say $150 a barrel), that triggers a bunch of interesting things. Some large off-shore reserves that are too expensive to develop become economically viable. That oil won't be cheap, but it will be available.
It also makes alternatives a lot more viable. A energy storage breakthrough could really be disruptive (in a good way), not only making electric vehicles viable, but also inconsistent renewable generation like wind, solar and tidal. If you could store energy when it was produced and release it when needed, the economics and logistics of these forms of generation suddenly become a lot more viable.
The company that can crack that challenge promises to be bigger than Microsoft or Google ... we're talking an opportunity that happens once every couple of generations.
Plus, the way we live in North America, there is a lot of room for efficiencies. Fifteen dollar a gallon gas would encourage people to live closer to work, to carpool, to use transit, to bike to the store, etc ... all good things.
Even with expensive fuel, though, there are some trips that the car is still king -- and I think people who could afford to would continue to drive for those trips. What you would see a lot less of is people commuting 5 miles to work in a 12 mpg SUV, which isn't exactly the end of civilization!