For gas prices to get this high on a sustained basis, you have to assume that either (a) shale gas will prove a colossal, over-hyped, mega-bust (something the Right is most definitely not in the usual business of positing) or (b) the U.S. auto-fleet will quickly transition to natural gas powered engines, driving up the demand for natural gas and, thus, the price.
FORBES: President Obama's Alleged "War On Coal" - Climate Change Edition