No, I think ONLY Republicans vote for him. I don't think he'd get hardly any of the mushy middle or crossover vote that is needed to actually national win elections. And if that is not bad enough, as a complete novice he is far too likely to do and say stupid things that blow up his campaign.
With the exception of Romney, any other Republican, even Ron Paul, can beat Obama. Any.
Yes, I see this same insane overconfidence on FR sometimes and wonder if the people that say this stuff actually have any real experience with, or understanding of, our election system and history. You do not know what the political conditions will be in Nov 2012, and you'd better be planning for a very tough, close election.