Actually, it leaves Newt, Mitt, Paul and Santorum (and Perry, but he'll be announcing his withdrawal any day now). That means that the anyone-but-Mitt vote is split three ways, which is a formula for Mitt to take the nomination, while the others jockey for second place. If Newt or Rick are smart, they'll offer the others cabinet posts in return for their delegates and endorsements. The next move depends on who is best situated to offer a deal (i.e., a clear runner up emerges). In that case, the runner up would be in the position to point out what I've just said, and that if they don't unite their resources, they'll be singing Hail to the Chief for either Romney or Obama in November. Newt or Santorum could offer Paul the Treasury slot if it meant that he could audit the FED. Paul or Santorum could offer Newt the State Department, which he'd have a ball cleaning out. Paul or Newt would have to figure out what to offer Santorum, possibly HHS, where he could actually make a difference in how money is spent on social services and enact real reforms.
Of course, if Romney is really smart, he'll start putting together a cabinet of serious conservatives to allay fears of his squishiness, including an appointment at HHS would would be guaranteed to gut Obamacare and not implement it until it can be repealed.