If he’s nominated he wont win. I doubt he’d even want to win since he would be ineffective at abolishing any of the government agencies, and since he’s nearing the end of his career. If he did, he’d be a one term president. He’s in his late 70s now and would be in his early 80s by the time his term was up. That alone is a huge reason why people wont want to vote for him.
I figure he’ll only run if he thinks it will spread “the message of liberty”. He is arguably the one who initiated the huge swell in the libertarian movement during the last 4 years, which has taken over most online conservative outlets, conventions (like CPAC) and spawned the Tea Party. I think he’s happy with that, and if he thinks another campaign will spread the movement even more, I’m pretty sure he’ll run.