I believe rather firmly in the 40-character limit, so I guess I should explain both why and who.
So, looks kinda limited(and it is, honestly, but thems the breaks). I guess I'll do the rundown of why these specifics are such. I could have probably scooted some things around a little better placement wise, but you get the gist.
Mario 5, Zelda 5, Pokemon 5. Nintendo's top three series as far as recognition and sales, and each would be represented equally(considering Yoshi and Wario are counted separately).
No Mewtwo? I believe Mewtwo had his time to shine and then he got pushed out by new talent. The only X-factor is his Mega Evolution, though with Greninja's reveal and Jigglypuff's very likely return(perfect attendance, mind you), I don't see Mewtwo making the cut unless he's a boss(which could work well with his Mega Evolution, either X or Y depending on various factors). Hate it all you like, but I think Mewtwo's officially playable status is dust in the wind.
No Ridley? Stage boss. People are torturing the logic and context behind "other boss characters appear" along with the Shadow. This is equivalent to hyping up Mr. X when any Mega Man fan knows it's Wily behind the facade. Newbies and people who get pumped up by seeing intimidating bosses get to salivate over what the dragon they'll be fighting might look like, but fans rooting for his playable status are likely to be disappointed.
No K. Rool? K. Rool hasn't been relevant in nigh-on a decade. Now, yes, you could say "Pit! Pit got in and he totally was dead for decades too!" but the things Pit had going for him was Sakurai's affinity toward Kid Icarus, an overall company interest in reviving older IPs(Punch-Out, Kid Icarus, Pilot Wings), and the fact that Pit is aesthetically pleasing to the eye(K. Rool's crazy pinkeye is.. Disturbing to say the least). K. Rool sports none of that(DK's revival was handled with Tropical Freeze), so he's incredibly unlikely.
Hey, you've got a Wolf icon in both your sig and your avatar, but he's absent from your roster? Let me clear this up right now. I like Wolf. I really do. He's a lot of fun for me to play and he's the only spacie that I play. That said, I consider Wolf to be one-and-done. He, like Mewtwo, had his time in the sun but I think he'll be put on a bus and shipped out somewhere. Either stage hazard, maybe a boss(fighting Star Wolf's Wolfen while atop the Great Fox or whatever), or only a trophy appearance. Now, common counter-arguments include "but Ike made it back, have hope for Wolf!" FE is a rising star and is also 'anime fantasy' which seems to have near-universal appeal. SF is an on-rails shooter whose most recent game is essentially a redo of the 64-era title, whose lack of popularity is further compounded by furry hate(see ANY Krystal thread). Falco gets in due to competitive popularity and tradition. Wolf has neither, so I don't see him returning.
ROB? I liked ROB. I never actually had one in RL, but I thought the idea of a robot that helps you play games was hella sweet. Maybe he can cut the mustard again ala G&W, but the peripheral's representative in WFT might knock him out.
Snake? Snake?! SNAAAKE!! He's dead, Otacon. If Kojima's claiming at this point that he hasn't been contacted for Snake, there's just no way unless Kojima is flat-out lying. Nevermind that they'd have to work with a new VA and fans of the character may be put off by it.
Chrom? Hey, I just read the trends. Blue hair, swordsman, main character of the most recent FE game. Ike's reveal shakes the theory up a bit, but I still think Chrom is sadly a shoe-in. Granted, I'm not a big fan of FE in general, so my bias is present.
The Sal Leak? I can't dispute it entirely, and WFT's prediction is definitely uncanny. That said, various characters seem... Unlikely. Palutena just doesn't strike me as playable. You'd essentially be bringing a goddess to the arena, and fans of her character might be dismayed with her lack of omnipotence were she set forth. Chorus Men look rather odd, but I'm unfamiliar with Rhythm Heaven so I lack the credentials to speak on their viability as far as a character goes. Mechanically, controlling three at once would be utterly bizarre unless they worked like IC, Rosa, or Olimar, and something tells me that's not what they're about. Shulk... I've not played Xenoblade, nor do I have any real plans to. That said, from observation, Shulk comes off as yet another anime swordsman with improbable powers and a 'cool sword'. While I feel XB is a bit too recent and obscure to warrant a playable slot, I have to concede that Sakurai did make a deal out of W101's trophy. My own preference is he not receive his invitation as well, but that's just me talking. Can you tell I'm not really an anime fan yet?