Are we talking people we think have a chance?
Brawl Vet Tier: (S Tier):
No reason to not bring those two back.
A Tier: 
,
Dixie Kong / K.Rool
I think Snake is easier to get back then people think. I'm sure he's at least being talked about especially since Kojima gave the okay. I expect a Donkey Kong character to be DLC. However, I only think we're getting one.
B Tier: Chibi-Robo, Isaac, Inkling?, Zelda Newcomer
These three are all new series. Inkling is only there because of promotional purposes. I'm rather unsure about them. But I can definitely see it happening. Isaac has popularity going for him but he's been out of the lime light for a while. Chibi-Robo is actually a semi-popular choice whos's been around since the NGC days and is STILL GETTING GAMES TODAY. I think people are underestimating him. If Sakurai is going for series that are still going strong that have characters that can actually work, then Chibi has a lot going for him. I just can't shake it, but I think Zelda's getting someone new. Impa is the most plausible choice, but it's not necessarily her.
C Tier: Reworked
, Bandana Dee, 


, Captain Toad
I don't think

will come back without their gimmick but I can see them happening I guess. Bandana Dee is certainly making a name for himself, but I don't think Kirby is going to be the main focus for a while. The remaining vets are all kinda unneccessary, but I feel they all have a real shot of getting in. Roy still has popularity and his gimmick. Pichu's niche is still untouched and Squirtle and Ivysaur were unique characters who probably only got shot down due to "Too Many Pokemon." Captain Toad I feel has a shot, but I'm not optimistic.
D Tier: Ray Mk III, Wonder Red, A Big Name Third Party, Metroid Newcomer, Krystal, Black Shadow
Ray is being a bit generous methinks, but I feel that the stars could align if given the shot. Wonderful 101 while kickass, bombed so hard I can see people ignoring it exists, though honestly, a character in Smash could turn that around. I also feel that characters like Rayman or MAYBE Layton have a good shot, but I think only the big boys have a shot. No Bayonetta. No Bravely Default. Nothing that isn't from a word famous series. They have to be legendary. Remember that. I have a feeling that we'll get Anthony or Rundas or something after the demand for Ridley fell through. I dunno, I feel like we might be thrown a bone here. Krystal has popularity, but I think Starfox U would have to be HUGE for her to have a shot. Black Shadow probably won't happen, but I can see him happening due to his voice actor's popularity in Japan.
I'd Be Downright Shocked Tier: Any Pokemon Newcomer, Any Fire Emblem Newcomer, Any Kid Icarus Newcomer, Any Yoshi Newcomer, Any Wario Newcomer, Any Mother Newcomer, Any Retro Newcomer, Any Pikmin Newcomer, Any Punch Out!! Newcomer, Any Xenoblade Newcomer, Any Sonic Newcomer, Any Mega Man Newcomer, Any Pac-Man Newcomer,
I don't expect any newcomers from any of these series or niches.
Sneaking Suspicion Tier: Any Pokeball Pokemon, Assist Trophy or Stage Boss
I can't help but I feel we're gonna get one of these through DLC. I just have no idea who it would be. My guess would be Isabelle but.. I dunno.