This whole thread probably belongs somewhere between the Green Room and the Ash Can at this point....
What will likely happen over time is that our mix of energy sources will change as economic and environmental factors make some sources more attractive than others. A good deal of the easily extractable crude oil is already gone. There's lots more that could be extracted economically at $100/bbl than there is at $20/bbl. If prices stay around $100, many other sources become competitive as well. Of course, subsidies mess up the tradeoffs, but high oil prices can only help make solar, wind, biomass, hydro, and other options more attractive.
In some cases, there are massive startup costs involved in developing a new energy source, but there are some interesting things out there. Methane clathrates might offer more energy that we ever got from oil, and it's worth reading up on the potential of
fourth-generation nuclear fission, regardless of what your feelings are about nuclear power. In the US, the technology that we're using for nuclear power is OLD. The latest technology is orders of magnitude(!) more efficient, and virtually eliminates the long-lived high-level nuclear waste. Maybe as oil disappears, we'll get a little less hysterical about the risks associated with nuclear. If we're going to have electric cars, we gotta have electricity, and lots of it.
Finally, back-of-the-envelope calculations are always fun. According to one study I've read, a well-managed five acre woodlot can sustainably heat one average home in New England. The United States has about 750 million forested acres. If half of that were managed and used for heating, that would be enough fuel for about 75 million homes, or somewhere between 1/3 and 1/2 of American households. Of course, we'll never have that many homes heated by wood, but we could do so sustainably if we chose to. Of course, the typical home in Georgia probably doesn't require quite so much wood to heat it ;-)