Worry about the base first and the moderates and independents later.
The conventional wisdom on Reagan for years before he won was that he was a conservative extremist with limited appeal who would kill the party with moderates and independents. Yet once those groups got a long look at him they saw the truth and he went on to win them in droves.
The conventional wisdom on Obama at one time was that he was too extreme to the left to win in the general. Both men began with enthusiastic base support which they cultivated into movements with wider appeal. That's the path to victory.
The base is the engine of the candidate. The bigger the base the more powerful the engine. Going after a nominee because of appeal to moderates and independents is a proven failure. It's hard to imagine a Republican nominee with more inherent appeal to moderates and independents than McCain. But that appeal never translated into the necessary grassroots enthusiasm.
Moderates don't motivate. Candidates like Palin or Jindal who are passionate and consistent advocates of the core values of the party do motivate.
So, which is it?
The thread has to do with Republicans seeing Sarah Palin in a mostly positive light. Since conservatives constitute a majority of the GOP base, then I think its fair to say Palin has most Republicans on her side.
What needs to be accomplished in the next couple years, is for Palin to turn around the perception by Independents, moderates and even some conservatives, that she is damaged goods. If she can't appeal to a good chunk of voters in the middle, she has no chance of being successful on the national political stage. Palin did help McCain get further than he would have otherwise, but still, many voters on the right did stay home on election day. Including many members of the Religious Right who would NEVER, EVER vote for McCain.