At the time I thought that probably closed her opportunity, although I personally understood why she did it.
It's way too early to crown any particular candidate the odds on favorite, but I must say I've been impressed with several during the Obamacare process. For example, Eric Cantor seens to be intelligent and articulate. Supposedly congressmen don't perform well in presidential elections, but I think he's developed some name recognition by taking Obama to task in his little ambush summit. Jim DeMint is another that seems to have comported himself well. I haven't done huge research on them, but they seem viable.
"Mrs. Palin, we know what it took to get you to quit in Alaske, what will it take to get you to quit in Washignton where the pressures are exponentially greater?"
They will clobber her with it.
As for Eric Cantor; I like him very much. his fatal flaw vis a vis electability is that he is Jewish. America is generations away from electing a Jewish POTUS, especially a conservative one.
As you said, it is early yet...