I think that's already happened. Some of the attacks on Palin before she had a chance to demonstrate her qualifications were disgraceful. Once having started defending her honor, the defenders had put a little of themselves on the line, making it harder to admit she was a dead end candidate.I think the criticism of Palin (much like the posts in this thread) actually endears her to millions of average people.
I don't think she will be the Republican candidate. However, if she does run - and more importantly is elected - it will probably be push-back to the personal attacks by the hard Left that makes it happen. Again, IMO.
Given a fair chance for people to form an unbiased opinion of her, I think the reaction would have been similar to the reaction Harriet Miers received as a Supreme Court justice.