So, if the leak is real..
One more time...
IF the leak is real,
then we're looking at a 'New Franchise', 'Popular in the West', 'Nobody is Expecting'.
Travis Touchdown, Doom Guy, Ryu Hayabusa, Waluigi, Geno, Steve, Crash Bandicoot, and Dante have all been considered endlessly, so IF the leak is true, then it won't be any of those guys.
Can't be Dixie either because it's supposed to be a 'New Franchise'.
Xenosaga is not what anybody would call popular; let alone in the west (the series wouldn't have died if it was 'Popular' in an entire region) so that's likely a 'nope' to KOS-MOS (plus she's arguably the same franchise as Shulk).
Rex/Pyra & Elma haven't really been talked too much about outside Smashboards (or too much at all as of late), but they are within the 'Xeno' series universe, so its kind of a toss up whether they can be considered possible for this particular fighter or not.
Rayman would be a new franchise and it's been awhile since he was discussed (the normal loop seems to be Pokemon, Dante, Doomguy, Crash, New Person, wash, rinse, repeat). I don't know how popular he really is though. Guess he's possible?
Obviously not everything we discuss as possible here on Smashboards counts as something 'people were expecting', but it shouldn't be too hard to kind of figure out what the possibilities are.