I've been saying this for months and months now - I don't get people who think there will be any significant number of cuts.
Snake might leave because of third party reasons. This will not be ideal, but it could happen.
Transforming characters would have left, except Sakurai took them and included them as separate character. I would assume that Squirtle and Ivysaur are gone, though, since they can't really stand up as their own characters like Charizard can.
Outside of special circumstances, I'm strongly of the opinion that no characters from brawl will be cut - Brawl's roster was concise and included almost all very important characters from its respective franchise. Very few characters could feasibly be cut.
R.O.B. is a vital piece of Nintendo history, especially in the US. Jigglypuff is a Smash veteran since the first game, and incredibly unique as a character. Lucas is the protagonist of a very popular game and an underrepresented franchise. Falco is a Smash veteran and a popular character, Wolf is a popular character with important ties to the Star Fox franchise. Ike is popular, especially in America, and was popular enough that he had a kid in Awakening despite all reasonable logic.
If anything I'm beginning to wonder if we'll just get seven Pokemon reps - Pikachu, Lucario, Charizard, Greninja, Mewtwo, Jigglypuff, and a grass starter. It's a lot, sure, but hey. It's Pokemon.