I don't buy it. I don't think she's electable. For every smelly hippie that votes for her, five apathetic conservatives will be motivated to vote who usually don't. I don't see her dragging out conservative Democrats, and she'd have to, in droves.
My prediction is that if Hillary runs, it will be the first election in a long time to break the 70% turnout mark, maybe higher. She is loved by some, and hated by many. If Democrats who lean right weren't persuaded to vote for her, she'd not have a chance.
I think you'll see the opposite. I think you'll see a more moderate Democrat next time. I think it will be a lot like the Bush Sr vs. Bill Clinton election. They'll pick someone with a 'down home' attitude, easy going, and no big agenda that seems outside the system. Granted, once they are in we'll see just how liberal they really are, much to our dismay.
Look for a democratic governor next time. If you want to be REALLY paranoid, imagine what would happen in McCain jumped ship... and anyone who wants to seem outraged at the thought isn't going to get much play from me. IMHO, McCain constantly proves he isn't above such a thing.