Ellen R. Malcolm says that "Winners never quit", which makes a great sound bite, but is irrelevant to the question at hand. Which person will do the best job of leading our country in the next 4 years?
If you consider the normal social behavior of following (that you agreed to in writing), Hillary is out of the race, and we have two choices left, McCain, or Obama.
Hillary isn't content to play by the rules, she wants to push Obama out of the race, at all costs, even though she can't win, because she's not the Democrat party choice.
However, Hillary is now so focused on power she's willing to do anything, even sabotage her own party (effectively campaigning for McCain). She's been following this track of desparation long enough now that I've been referring to the McCain/Clinton 08 ticket for some time now.
While I would certainly welcome an Obama/Paul ticket (the only 2 sane candidates who ever had a chance in the first place)... that's not in the cards.
Hillary is now playing to role of Ralph Nader, and spoiling the election for the Democrats. So, we'll see Hillary play some role in making sure the Bush-Clinton dynasty gets handed off to it's chosen successor, with a possible re-run by Hillary in 2012.
Don't you think 28 years of Bush-Clinton is enough?
It's time to give the people a chance to run things.
Update: John Aravosis says it even better (with less rant, and more logic).