I don't know what he'll do. But what I think he should do is get his independent ticket going (and I'm sure he's already working on it). This time around, I really feel that a third-party candidate could outweigh the tired old two-party mentality. We're all starting to realize that the two sides of the isle are funded by the same corporate interests, and Ron Paul should already start knocking at the supports of the two-party system, while he's still got the podium at the Republican debates. He can ride his main talking points later, when he gets to go head-to-head with Obama AND Romney. It will be harder to knock the system later, because he'll be under direct attack from BOTH candidates.
(Because it is clear they'll never let him win the republican ticket - even if it means flagrant ballot-box fraud, right out in the open in front of everyone).