she would be the presumptive front runner in '12 or '16 if they win. in fact, if he wins, she is virtually unstoppable all the way to the white house in one of those two years. vice presidents always win.
Is that you, Al? 
LOL! I had written "barring some distasteful scandal", but I backspaced over it. I figured everyone would know what I meant.
I think it depends on McCain. If he goes back to his "gang of 14" style of governance whilst in office and Palin gets swept up in that, being the loyal Veep, should could loose the base out of the gate. But if McCain is seen as not-pandering-too-much to the NY Times/liberal side of the aisle then she has a decent shot. She seems really intelligent though so I don't think that will be an issue. Still, one never knows how an elected official will act once they are in D.C.
it's all a mater of one's perspective, and how that would change after the election. a senator probably believes in the preeminence* of the legislative branch of gov't, and acts accordingly. a president believes in the ascendancy* of the executive, and acts with that view primarily in mind.
the short version is that I am sure he would be a different kind of president than he was a senator.
*
when I say "preeminence" and "ascendancy", and am merely referring to a "first among equals" relationship.