There are backward hillbillies all over the U.S. who won't vote for a woman unless she has a firmly established brand name, and Hillary's got it. Also her husband is very popular.
With that said, her opponents will remind everyone that Bill got impeached. Also, if he has another extramarital affair that goes public (especially while Hillary is president) and she doesn't divorce him then everyone will view her as a pushover who lacks the courage to be a good commander in chief in a world that's blowing up.
If the first female president falls flat on her face then it will be almost impossible to get another woman elected for a very long time. Hillary was in D.C. for so long that everyone already knows what her strengths and weaknesses are, and her husband and staff know it, too, and so they'll hire reinforcements. In other words, voters who are still angry because of Benghazi will be assured that it will never happen again, and those who heard that she copied other senators' votes while she was in the senate will be assured that that will never happen again.
My fear is the possibility of nepotism and cronyism: Inappropriate, illogical hiring. For example, she may give her daughter Chelsea a high wage job in senior management. Some people would say that it would be fine, but in my own opinion Hillary and Bill sheltered Chelsea way too much and she grew up to become a perpetual student and now a rich housewife, which is exactly the opposite of what Americans need at the White House, especially during our slow economic recovery, bloody wars overseas, and terrorism right here on domestic soil.