Gasoline in the range of $2.50 per gallon would be possible much more quickly than you may think. During the Arab oil embargo of the Carter years the price per barrel was pretty high. Deregulation under Reagan started a domestic energy production boom. Arab countries started flooding the market with oil, the price of which dropped like a stone. Because of the lower price (and profits) domestic drilling slowed...but we had much cheaper energy costs, which helped fuel the great economic expansion that resulted. We start drilling...the same thing will happen again. The Arabs are nothing if not predictable.
The 40th posts says the magic word, "Deregulation." :-)