Well, the future price of oil depends on how much demand is killed from the current high price of oil. I love seeing Americans getting on the ball and buying small and efficient cars. See, we don't need no stinking movies, Al Gore yapping (Thanks Al) about global warming, peak oil doomsday ranting, terrorist theories, etc. Nope, all we have to do is rise the price. That's when people pick up their collective heads and say, "Huh?".
So, If we start getting tons of plug-ins on the roads as well as have people cutting back by good percentage then the price will come back down, assuming China and India don't just suck up that excess and more (this is likely). If you look at how us Americans live you can see we have a long way to go towards efficiency. Look at cars in Europe and then look at our cars. Hummm.
However, If we don't make a good effort to stay ahead of the oil depletion curve by converting our oil usage by an equal amount each year then the price will creep back up and make people cut back more. This is how the world will yo-yo to renewability. Though pain and suffering. Smart people will look a few years down the road and say something like, "Hey! This looks like a long-term trend. I think I will prepare for this and get solar panels, an electric car, plant a garden, collect water, and build a green house." Since these smart people will have reduced their energy needs to such a great extent they will be able to handle cost increases of petroleum products (which include just about everything) much better than others. After all, wealth is a state a mind where you are perceived as better off then the people around you. The lucky kid on the block is the one that has $100 bucks while the rest have only $1.
Of course if things really go badly then people will be dying of hunger in shocking numbers, bickering over remaining energy resources will lead to wars and civilization will go into a dark period of long-term economic and social retraction. So, it's kind of important that we stay ahead of the curve, don't you think?