If Hillary doesn't run, then it becomes VP Joe Biden's nomination to lose.
Perhaps it would incentivize Elizabeth Warren to run.
Bernie Sanders is thinking of running as an issue candidate to bring awareness to economic policies that are having the effect of creating drastic levels of income inequality.
Then there's Govs. Warner, Cuomo and O'Malley. I don't think he'll run in 2016, but maybe at some point beyond that, Cory Booker might run.
With Hillary out, I'd have to go with Biden. The most intriguing thing about him is that he'd be the first President since Lyndon Johnson who appears to have no filter. When they speak, it is definitely coming from the root of their own lived existence. They don't ever seem poll-tested, pre-conceived, or pre-packaged. Biden is never boring. And he's the only candidate on either side at the moment who can actually be really funny.
Biden's got the elder statesman thing down and he's folksy, which is popular with older white people. The only candidate I feel could win a big landslide victory is VP Biden, if he runs things right. He'd naturally bring back into the fold a greater percentage of older white voters than what Obama got. Add Obama's young base to that tally and Biden could potentially start running a wave across the map even making places like Missouri, South Carolina, and Georgia competitive.
America is not adverse to voting for the smiling folksy old white guy. They love that guy when they find him, and Biden is well-cast for that role.
I think if it's between him and Jeb, Biden wins. I think there's serious Bush fatigue out there still. You can tell as much from moderate people who just roll their eyes when Bush's name comes up. It's that look that says, "Oh what a dumbbell that one turned out to be".
Hillary is a more polarizing figure than Biden. Notice how Benghazi at first was a conspiracy in order to get Obama re-elected? That's what Republicans first trotted out there as being the whole point of the scandal. But now they tell us it's all really about Hillary and the whole point of the conspiracy of Benghazi has now evolved to, "Hillary was happy to let Americans die in one of the worst instances of criminality against America maybe even EVER!".
With Hillary as a candidate and then possibly President, look forward to more of that derangement syndrome Republicans have about minorities and women. With Biden I feel like a lot of Republicans are going to find it hard to make anything stick to him because no one would ever accuse Biden of being some shadowy, underhanded, typical politician. He's like this charming, grandpa-with-energy guy whose gaffs are often really funny and endear us to him because he's the first to admit that he gets carried away in the moment.
Biden/Warren would be a serious ticket to contend with. I'd vote for that.