Right now the campaign is just beginning, personally (if she runs) I believe she will have a harder time winning the GOP nomination than winning the general.
Do you honestly believe that in the middle of a campaign where the public is actually being reminded daily of Obama's record, and they are actually dealing with the real image of Sarah Palin on an ongoing basis those precious independents and moderate republicans are going to vote for Bambi?
You really think that?
Well, all time is doing is reporting the numbers.
Reagan was down by 30 points right after the Iowa caucuses, but all of Carter's opponents were down then. The country was responding to the Soviet invasion of Afghanistan and the Iranian Hostage crisis by rallying around the president ("Nation: In a Fiercely Hawkish Mood", Time Magazine, 2/11/1980). By April of that year, Reagan was tied with Carter ("And Reagan Catches Carter", Time Magazine, 4/14/1980). Just a couple of weeks later, Reagan was leading by almost 10 points, causing heartburn for the Dems("Squalls Among the Democrats", Time Magazine, 5/19/1980).
And let's not forget that Reagan's numbers were kept down after the convention by John Anderson running a 3rd party campaign. If not for Anderson, Reagan would have been up by 10+ points all summer and fall.