I remain very curious to see if Clinton will agree to debate Sanders (should he be her lone challenger). And in general, how well he would do. Of course he's not going to win the nomination, but Clinton (like any frontrunner) will inevitably have a bad week, a gaffe, whatever. If Sanders is her only challenger he'll get at least some play, and he'll be the face of any discontent with Clinton within the party (and there will surely be *some*). It's unclear how far he can go with that. Clinton is still the favorite in all 50 primaries, but Sanders would inevitably do better than the 1% or whatever he's polling at now.
don't be surprised if he gets everyone excited by pulling within single digits in a few Univ of New Hampshire polls either