Tonight looks like it'll be a pretty bleak night if your name isn't Romney. Gingrich will win Georgia, but won't get back 50% so it'll be by congressional district and Romney might be able to pick off some of those delegates, Virginia and Massachusetts are non-contests, and the fact Mitt is running only about a point behind Santorum in Tennessee really spells the end to the idea that "anyone but Mitt" might run away with this.
The race up until this point has been about narrative, and it would be hard to imagine waking up to another Colorado/Minnesota/Missouri surprise. At this point Santorum is just shooting himself in the foot left and right, no one is willing to give Gingrich another surge because we've seen him fall too many times already, and Paul will never appeal to more than 30% of the electorate. The narrative is now that Romney has repeated beat back his opponents with his superior money machine and organization at the state level, even though much of that "organization" is a single office in the state it's still comparatively better.
So if Romney wins Massachusetts outright, a popular/delegate advantage in Ohio (bonus points if he wins by more than 5%), picks up some delegates in Georgia, takes all of Virginia, gets close or wins Tennessee, and doesn't get romped in Oklahoma/the caucus states he's going to lock this thing up in all but name. He'll have trouble in Alabama and Mississippi, but if he does better than expected in Tennessee and Oklahoma tomorrow he might sail through the states on the claim of inevitability. Republican voters will start seeing the advantage he has and settle. And after that it's even smoother sailing.
Now a warning. This contest seems to settle into the paradigm for just long enough to have people think they've figured it out, and then we have the revolt in South Carolina or Santorum's triple win. In the end Michigan really was the "anyone but Mitt" contingent’s Waterloo. The media keeps building them up only to have them torn down, first in NH, then Florida, then Michigan and Arizona; eventually voters will start listening less to how a candidate is doing right now and focus on the long term.
Romney continues to have an enthusiasm gap as compared to the supporters of Santorum and Paul, but in the general election much of his base will be made up of disaffected moderates who will be voting against Obama more than for Romney. The attacks of Romney’s moderate tendencies may in fact help him in the long run if a majority of the Republican electorate recognizes that he is their best bet to beat Obama.
After Super Tuesday we'll finally see that Republicans may not have fallen in love with Romney over the last few months, but they're going to fall in line to beat Obama.