To be honest, I think the DLC is probably already largely locked in place, but I think there's more beyond this.
The DLC - we're almost certain to get the missing Smash Veterans - Mewtwo & Lucas are already confirmed. Wolf'll follow, I'm sure. They also have scope, if they want, to adapt Squirtle & Bulbasaur into full characters derivative from how they play as Pokemon Trainer in Brawl. There's also a few characters rumoured for Brawl that were very likely cut based on content found on the disc (like the Chorus Men) and stuff.
I think anybody who has any existing asset is more likely to make it in. I think Golden Sun's Isaac is a very interesting case, as well: He was an Assist Trophy in Brawl, and despite the fact almost all the Brawl assist trophies appeared in the new game completely untouched, Isaac was absent entirely. Maybe he was destined for greater things...
Beyond that, I think Nintendo would be mega smart to prepare a Super Smash Bros for NX for launch day. It doesn't need to be a whole new game - just make it the Wii U game with balance changes, plus DLC, and with some new stages. The community will eat it up. Nintendo is gradually starting to embrace the rerelease culture, and post Wind Waker HD Iwata has made clear they intend to do more. Basically, I think the tail of this survey's result could extend beyond Wii U.
