I don't follow at all. Unless GWB loses his base, he wins the election. It's not Dean's (or anyone else's to win); if it were to happen it would take a major Republican blunder.
A real lot of Republicans will be Democrats on their primary day, since there is no race for us. <^..^> Anyone sensible will be voting against Dean in the primary, helping the Democratic faithful get rid of this danger to the nation.
Besides that, what track record does Arnold have? California is a mess. It needs an experienced, proven political figure to solve its problems...not someone with no track record in governing.