My top 3 most likely:

King K Rool (main villain of DK, often requested both in the West and Japan I think)
Wolf (often requested, veteran so seems easy and likely considering Mewtwo, Roy and Lucas)
Inkling (major new ip and very succesfull. Probably popular enough in the west but I expect Japan to have massively voted for it)

I can also see Bayonetta or Isaac happen. Or maybe even Simon Belmont considering the iconic 3rd party characters we've been getting.

Shovel Knight has a lot of support in the west, and we already have an Amiibo on the way. But it don't think an indie character of a game not even released in Japan yet is very likely.

Wolf
Snake
Isaac
Ridley (Still)
Inklings

If one of them could at least be Bomberman, Smash would be complete for me... @_@

Goku, John Cena and Chuck Norris are going to win! Can't wait to play as them.

I could see the Inklings being one of them If Nintendo wants to really push this New IP more.

I could sense 1 more pokemon to be in it. But im not a Pokemon fan soooooo IDK who could it be. But Greninja was a very popular pokemon in X and Y <---- so that could be a reason why he was in it.

I can see W101 to be in it. And if Nintendo wants to do some double Platinum in smash, they can add Bayonetta too .

An anime character would be awesome as well. - Naruto? Luffy?