The GOP could run an actual conservative (social and economic), unlike the last few POTUS candidates(1).
Looking at the numbers on 2012, BHO got fewer votes than 2008, but Romney got even fewer and barely beat McCain's numbers in 2008. Looks like the conservatives were not fired up like they were in 2010, when lots of GOP candidates claimed Tea Party sympathies. OTOH, Romney showed the Tea Party his buttocks...and they stayed home.
The GOP can still win, it just needs to not run away from wildly popular issues (immigration restriction, & others), not piss all over its coalition members (how well did de-emphasizing social conservatism work in 2012, huh?), and offer an adult alternative to the drunk teenagers driving the federal family car.
Of course, if 3rd world immigration is not stopped and massive and ruthless efforts not made to assimilate those already here, the future is in the cess pit.
(1) 1980, 1984, 1988 are the last conservative campaigns the GOP ran. GHWB in 1992 was a confirmed squish by his actions. Dole 1996 was a GOP establishment, "tax collector for the welfare state" candidate. GWB2000 tacked rightwards, and was lucky the Dems chose John Kerry in 2004. McCain 2008 was Dole, only even more bellicose on foreign policy and as much an economic ignoramus as BHO.