Dixie Kong
Likelihood - 60%
Let's nip an old and tired argument in the bud right off the bat, shall we? Dixie being part of the Forbidden 7 means virtually nothing, for multiple reasons. It's selective reasoning used to support her and not characters like Doc and Toon Zelda, first off. "Sakurai revisits old ideas" is equally selective, considering for every idea he revisits, like Villager, Dedede, Mewtwo and Final Smashes, there are ideas he leaves in the dust, like Balloon Fighter, Sukapon, Urban Champion and the Excitebike Racer. "Sakurai thought about how she would move" is yet another poor argument, since Villager is living proof that not every character Sakurai has "thought about" in the past is visible on Brawl's disc as data; he could have thought about thousands of characters, for all we know. And if Dixie is to be planned separate from the duo she was originally intended to be in (a likely case, since duos are causing trouble on the 3DS), more thought in her moves would be needed anyway, to the point where she's virtually level with any other newcomer.
That said, as one of those newcomers, I think Dixie has a decent shot at earning her way into playability. For as often as confused speculators claim she's competing for a DK series 'slot,' they neglect that the roster isn't a legislative body full of representation quotas, but rather a hodge-podge of Nintendo's all-stars, which she definitely qualifies as. According to fan polls, her popularity is middling in the West and above-average in Japan, giving her some degree of support to her name as well. Lastly, her capacity to take Diddy's moveset and Luigify it is worth noting, since she could easily replicate his acrobatics and tail-based moves using her hair, while diversifying them up enough with her own tomboyish flair.
Oh yes, and as much as I detest the "relevance" **** that is bound to follow, I think Tropical Freeze bodes well for her inclusion for other reasons. It doesn't render her likely just because she's in it; for all intents and purposes, a single new DK game without her post-TF is enough for those pundits to forecast her chances right back in the rubbish heap. What's key about the game is that it's another notch on Dixie's belt as far as importance goes; she's now no longer the sidekick to a sidekick, but is now teaming up with DK himself. If that isn't a solid all-star credential, it's tough to say what is. Really, Sakurai is all that's majorly standing in her way; since he touted the importance of 'uniqueness' in his interview the other day, it's feasible that Dixie could fall through the cracks due to lacking it, beyond bizarrely pulling juiceboxes and Animal Buddies out of thin air, as occurs in most fan movesets.
Want - 50%
She's a mixed bag for me. I'd go ape for the additional Donkey Kong representation, especially since it opens up the door for more content from DKC3, her big game. That said, 'a character with a third arm' (the third arm being her hair) doesn't have immediate appeal to me; I'd probably save playable Dixie for DK series battles of all three Kongs vs. K. Rool, because heaven forbid such nerd dreams actually happen in a DK game.
Pacman Prediction - 59.5%
His relatively small number of fans on this site will unite with the recent leak believers to balance out his detractors well enough.
Nominate:
Little Mac x3
Mewtwo x2