Matthew Dowd plays the parlor game:

If Republicans nominate an extremely polarizing figure who has a difficult time getting independent votes (especially in the crucial Midwest states) or one who instills no passion at all in the conservative base, and if Obama’s approval numbers stay low, then we basically would have two unelectable candidates facing each other in the general election.

Ed Morrissey is skeptical. Erick Erickson can only interpret Huntsman's impertinence as the rumblings of a third-party candidate: 

He is slamming the other Republicans. He is smearing Iowans. He’s burning every bridge within the GOP. The only other place to go is to endorse Obama or claim to be a third party “middle way” candidate.

PPP runs the numbers, complicating Dowd's scenario: