So...
1. Shulk
2. Mewtwo
3. Ridley
4. K. Rool
5. Dixie
6. Krystal
7. Bandana Dee
8. Isaac
9. Takamaru
10. Chrom
It really does feel like we're coming to the end of things. The incoming Direct is likely to knock out at least one of these giants coughhorkhackshulkohmygoditssoobviousatthispointholyhellletsnotkidourselveshackhorkcough and I wouldn't be surprised if at least one of these were disconfirmed leading up to it. Though, looking at this list, I'm kind of surprised that all but two that are remaining are leftovers from the Brawl riots...
Alright... going through that list...
1. Shulk - Very likely, based on several hints by Sakurai and devs. from Xenoblade. Not to mention that he's a FP character.
2. Mewtwo - Once again, very likely. Most-wanted in Japan, and Sakurai has hinted at him, saying he's a possibility.
3. Ridley - Very likely. The prolonged teasing of Ridley on Pyrosphere leads me to believe that there's more to it than meets the eye.
4. K. Rool - Likely. The DK franchise could get a third rep... and the only one in his way is;
5. Dixie - Likely. The challenger to K. Rool's rule.
6. Krystal - Semi-Likely. If SF is getting a forth rep, it's most likely going to be her.
7. Bandana Dee - Unlikely.
IMO, his importance to Kirby is a bit overrated. He might as well be a more recent Gooey.
8. Isaac - Semi-Likely. He, unlike most of his Brawl AT friends, hasn't been seen yet. Importantly, he's a FP character, but he could go down the route of Takamaru.
There you have it. The official MaskO'Gears speculation chart. Feel free to pick it apart to your heart's leisure.