Not only are Americans tired of the Bushs and Clintons, I think if Hillary gets the Dem nod the possibility of a vicious, beyond dirty campaign might turn a lot of people against her too.. If she gets the nod we know the Republicans won't stop at anything to beat her, they already are bringing up Monica and saying Hillary has brain damage. The GOP is already in the gutter..
BUT the Clinton's, and their machine are much more capable of getting down and dirty than Obama.. Obama's actually been pretty civil when we look are how vicious and dirty the GOP has been towards him.. In 2016 whoever the GOP nominee will be brutalized by the Clinton machine..
And that actually might turn off some people, even within the Dem party. People might want the Dems to try and pick someone who is less controversial then another Clinton. Of course a lot of that might depend on the Republicans.. If they keep moving further to the right, and it looks like someone like a Cruz would get the GOP nod, then the gloves will come off, and Hillary will be the Dem nominee.