By the erstwhile tradition of the GOP - Romney is doomed. Santorum did just fine for his first run out winning 10 states off Romney the 'inevitable'.
Or do you forget that's why it was Romney's turn this time?
Why would conservatives want to go for someone like Rick Santorum over someone like Marco Rubio, Bob McDonnell or any of the other stronger conservative candidates who are up and coming or didn't run this time? Santorum is not a good candidate at all. He can't stay on message and he lacks discipline. His debating style is one of the reasons he didn't break out sooner, because people saw someone who looked like he was constantly pissed off. He makes gaffes and then doubles down on it and then blames the media if it costs him in the end. That doesn't work. I think the Republicans will be looking for a fresh start in 2016, preferring to just wash their hands of this horrible cycle and all of its lame candidates, especially if Obama gets reelected.
Santorum at best will end up in 2016, like John Edwards running in 2008, at worst like John Kerry's abortive 2008 effort and/or Dan Quayle's attempts.