The fact that Reggie has been referring to this reveal as a "fresh look" (or some similar vernacular) makes me think they're just going to show off Cranky Kong in Donkey Kong Country: Banana Slamma and probably Bayonetta 2. Smash Bros. is still too far off, and there really aren't any new characters they could reveal that would make a major impression against so many actual game reveals at the event. I just don't see Zelda or X making an appearance at this event, nor SMT x Fire Emblem. Two of those are too early in development, console Zeldas practically live off their E3 reveals, and I just don't see Nintendo having enough confidence in X to release a substantial trailer for it at this event.
We won't see a new Nintendo game reveal at this show, not when Nintendo can't control every aspect of the unveiling and the messaging.
Ultimately, whatever Nintendo shows can only underwhelm people. This isn't the kind of event where Nintendo would drop a megaton. For that, we'll probably have to wait for the Q1 2014 Nintendo Directs and E3 itself.