I disagree. Palin, if she announces, will be fighting for the conservative wing. Cruz and Paul already have their supporters locked. Palin may pick some support up from the Perry or Huckabee or Santorum supporters should any of those men not run, or run and drop out. But she's trailing the big two right now and an announcement won't change that.
Oh please....no one's running yet, and no one's got supporters "locked up". This time next year, we'll still be about a year and a half away from election day, so it's still waaaay to early to be talking real baseball.
A whole lot is going to happen between now and the start of the real horse race. We've got a midterm election to focus on first. That's a lot more important (and forecast-able) than the 2016 presidential election.
Lastly - do not underestimate Sarah Palin. She's proven the doubters, natterers, and naysayers wrong on too many occasions to count.