People were asking the same question in 2008 remember? We all know how that worked out.
The candidate that can beat Hillary Clinton will be the candidate that can focus the country on financial issues and keep the social issues, like gay marriage and abortion access, off the table or at least very far in the background.
I suspect by 2016 the Stock Market will have "corrected" and there won't be much economic improvement. That makes any candidate that can be associated with the "current administration" vulnerable, which is probably why Hillary bailed out. She'll be less vulnerable.
Let's understand the country as it is today and will probably be in 2016. You need a reasonably center of the road candidate who (1) doesn't scare Blacks and Latinos, (2) single women can live with, (3) can't be branded as a complete kook because of things he or she has said or done in the past.
Hillary Clinton meets that profile but who else?
The profile pretty much lets out Joe Biden as well as far left people such as Bill DeBlasio and Mario Cuomo of New York on the Democratic side and just about all of the extreme Right Wing types such as Rick Santorum, Ron Paul, Ted Cruz and Rick Perry on the Republican side.
The Democrats wouldn't be able to win the nomination and the Republicans wouldn't be able to win the general election.
Chris Christie looked like an interesting possibility but he might be self-destructing. Besides, exit polls in 2013, an election Christie won easily and in which many Democrats didn't even bother to vote, showed he would LOSE New Jersey to Hillary Clinton.
Jon Huntsman would probably have a good chance in a national election but look how well he did in the Republican primaries last year.
So who's left? I don't know but I didn't think Barack Obama could pull off what he did in 2008 either.