Now, I don't agree with this guy's conclusion. But he sets the stage very well, and lists all the alternative power techniques that I know of (and a few I didn't) in good detail. So if you're interested in this, it's worth reading.
Note that he seems to be slightly out of date on the hydrogen storage issue, however - there have been interesting developments in that field.
The cost of gas will continue to go up until the Canada tar fields start producing heavily. It will level off for at least a decade at that point. (Note: this does not mean "drop". The days of under-$2-per-gallon gas are over for the foreseeable future.) There are several ways the energy economy could go from here.
* Thermal depolymerization could become far more widespread. This won't solve the problem. It will give us quite a bit more breathing room - potentially a decade or two, if my wild speculation is correct. :D
* The various green power sources could become far more widespread. I don't believe this will solve the problem either. But it may, again, give breathing room.
* America could re-legalize nuclear reactors. (Yes yes, they're not technically illegal - just the nearest thing to it.) IMHO this would be the best solution, by far, for America.
* Canada and Mexico could super-legalize nuclear reactors, hook their power grid into America's, and get insanely rich of America's stupidity.
I don't see any other practical solutions within the next few decades. I do not believe that solar power or wind power or tidal power can supply all of the necessary capacity at a reasonable cost. Fusion power would solve *all* our problems, and while I'm confident we'll have it someday, I think we're at least half a century out. So, IMHO, it's basically down to nuclear power plants and some damn good recycling.
"But Zorba", you cry, "What does this have to do with the price of gas?" Well, it's all down to energy at this point. And we're going to have an energy economy up until the day power is literally to cheap to measure (that will be the day the first human-portable gigawatt power plant is produced, I suspect - don't hold your breath.) "The price of gas" isn't really what you're interested in - what you're interested in is "the amount of money it takes to move my car a mile". And that may, eventually, go down, because that number is a fixed number of watts, and electricity will keep getting cheaper.
Incidentally, the price of gas *may* eventually drop below $2/gallon again. But it'll do so long, long after your car is running on something else - electricity or hydrogen, I suspect. (It depends on which storage problem we solve first.) And it will do so because synthesizing artificial gas - a process that takes a terrifying amount of energy - will become cheaper than mining it or dredging it or drilling it or extracting it, thanks to incredibly cheap electricity.
So it's basically all revolving around Power, in whatever the most convenient form is. As that gets cheaper, everything gets better. Everything. (And I'm not being my usual exaggerating self here, I honestly mean that. Everything.)
This could likely be more coherent. But now I'm going to bed. Feel free to flame my love of nuclear power. :D