IMHO, plenty of other Democrats would have about as good a chance as Clinton in the 2016 GE, if they were to win the nomination. But the others don't currently have her name recognition, so they're not going to show up as being all that strong in polls taken right now. (And of course, she'll probably be the nominee, so this proposotion won't be tested.)
Name recognition is certainly a factor, but it's not the end all be all. Hillary still leads Republicans who have high name recognition. Conversely, when low name recognition Ds are tested against low name recognition Rs, the R still tends to have an advantage.
Also, Biden's name recognition is as high as Hillary's, and he tends to do markedly worse than Hillary in polls. Ex:
Biden's gaffe-itis and image as a buffoon is a terminal drag on his electoral chances. But if, say, Gillibrand or Klobuchar had the name recognition that Clinton has, I think they'd do about as well as she does in head-to-head matchups against the GOP candidates.
