You hear a lot these days about the chaotic state of the GOP race, which is obviously true insofar as lots of candidates still have a shot at winning. But I don't think it's true in the sense that several candidates have an equal shot of winning.
My sense is that Mitt Romney emerges from Michigan with some pretty clear advantages. For one thing, the first kind of chaos ("type 1") makes it pretty tough for Romney's rivals to raise money, which will, perhaps more than anything else, influence the outcome of the 21 February 5th contests. As this Politico piece notes, the GOP's general fundraising environment was already tough. Type 1 chaos doesn't make it any easier--both because people are reluctant to bet on a potential loser, and because the bettors end up splitting their money among several candidates. Romney's personal fortune is obviously a huge help here.
Second, Romney doesn't need enough money/momentum to win the nomination outright. He just needs enough money & mo' to survive a winnowing of the field down to two candidates. Should he make it into a one-on-one scenario with any of his four plausible rivals (I don't consider Fred Thompson plausible at this point, though he could prove me wrong Saturday), I suspect the GOP establishment will rally around him with lots of money and support.
The reason is that each of these rivals inspires much discomfort in some significant corner of the party establishment. There is deep suspicion of McCain among lobbyists (hard feelings over Jack Abramoff), anti-tax people (particularly Abramoff pal Grover Norquist), and the various interest groups (gun-rights, anti-abortion, etc.) whose lives McCain made more difficult with campaign-finance reform. And that's before you get to the evangelical leadership, which hasn't forgotten his "agents of intolerance" diss in 2000. (See this recent Washington Post piece for a complete list of establishment McCain-haters.)
Meanwhile, Huckabee provokes all sorts of fear and loathing among security hawks and supply-siders (whom he derides as part of the Wall Street-Washington axis), while Giuliani obviously has his share of problems with the social-conservative industrial complex.
Romney has no such problems. While grassroots evangelicals may have their doubts about him, the elite portion of the movement likes him just fine. Supply-siders seem swayed by his businessman cred while the hawks take comfort in his obsession with doubling Guantanomo and jihadist caliphates.
Now run through the practical scenarios:
If McCain wins South Carolina, Huckabee and Fred Thompson are finished. (Thompson for obvious reasons, Huckabee because the state is about as ideal demographically as it's going to get for him. If he can't win there, where can he win?) I suspect Rudy is done, too, since he and McCain appeal to similar voters--security hawks, social moderates--and McCain will have all the momentum. That means a Romney-McCain playoff.
If Huckabee wins South Carolina, Thompson is done and McCain is damaged goods, while Giuliani and (obviously) Huckabee are still alive. With his war chest, Romney should be able to sneak into the top two in Florida, and the person who falls to third--Giuliani or Huckabee--is probably done, too. That means a Romney-Huckabee/Giuliani playoff.
If Thompson somehow wins South Carolina, Huckabee is done, McCain is seriously damaged, and Romney has a great shot at first or second in Florida, since Thompson will have a steep hill to climb there.
The biggest risk to Romney is a fourth-place finish in South Carolina, which raises questions about his viability and sends him limping into Florida. That's probably why you see Romney continuing to run ads there even though he's ostensibly conceded the state.
Short of that, I'd say his prospects look pretty good--or as good as they can in a race this wide open.