Third Party Candidate in 2012?

Even though I've been out on politics for a while, the buildup to the Massachusetts election sucked me back in; so I've been thinking a lot lately about 2012, both in terms of who I'd like to see run, and who is likely to run. I may handicap the Republican field at some point, but the main thing that struck me is that 2012 could set up as the best election cycle ever for a third party candidate who was willing to spend lots of his own money, namely Michael Bloomberg. It's tough to tell where Obama will be in two years, but I think it's probably a fair guess that Republicans will win big in the mid term elections, but probably not big enough to take back the House, and certainly not enough to take back the Senate, and I think their failure to do so will actually hurt Obama. In 1996, Clinton could point to the failures and corruption in the Republican congress, but if both houses are still controlled by Democrats, that will be an advantage Obama doesn't have and could hurt his chances at reelection. On the other side, lets pretend the Republicans do something stupid and nominate someone who is unelectable like Palin or Huckabee (I don't think this is likely, but we're pretending). In a three person race between Palin/Huckabee, Obama with a close to 50% approval rating, and Michael Bloomberg, I think Bloomberg would not only have a chance to take a large number of electoral votes, not only have a legitimate chance to win, but I honestly believe he would have to be the favorite. Even if the Republican nominee was someone like Haley Barbour, Newt, or Tim Pawlenty, I think Bloomberg would be in pretty good shape. The only nominee who would seriously cripple his chances I believe would be Mitt Romney because he would also have strong business credentials.

So what do you think? Is my analysis right or wrong? Or is Romney such an overwhelming favorite to win on the Republican side that my scenario won't happen?