Ye forgot about the Donkey Kong Country series as well ;)
Well I dunno, Pac-Man may slightly have a chance of being in it, for the sole reason that Nintendo, Sega and Namco DID join together to make an arcade company Triforce Entertainment I think...
And well Sega is Nintendo's right hand man now so Sonic just may be in it. If he is, they should also put in Tails and Knuckles.
And they certainly do need more Kirby characters, King Dedede, Meta Knight, etc.
I dont know if they'll have any more Pokemon, they may though because of the not-so-new-anymore R/S series. But I mean they already have.. Pikachu, Pichu, Jigglypuff and Mewtwo... I dunno they may be able to fit some newer Pokemon in it, Jirachi or Deoxys maybe... I hope.
I dunno, they can only have so many characters in one game, ya know? I mean I dunno if they'll be able to add like 3 more characters to each game series they already have included plus like 5 or 6 new series' with about 2 or three characters from each. They might though.
They better not come up with some cheesy bad pun for a title like Super Smash Bros. Threelee or something, I'd have to shoot myself. But I doubt they will. They'll either go with SSB3, SSBM2, or Super Smash Bros. (insert some cool fighting game-related word thing here) or something. I guess thats sorta off-topic though.