When the price at the pump (and I'm well aware that PO is about A LOT more then the price at the pump) reaches $6+/gal, people will complain like babies in the terrible two's. But do you really think they'll stop driving their SUV's? I don't.
I think I remember hearing about a study on NPR that said that people would start to dramatically alter their driving habits at about the $3/gallon range. Who knows if this is true or not, but I think things will be a lot different. Take a look at places like the UK... petrol is $3/4 a gallon, and people drive less, drive more efficient cars, etc... (compared to the US...)