I just thought something. Smash is having a huge marketing campaign right now, however it's mostly for the 3DS, as that is launching first. How are they going to keep the hype high for the Wii U version? Probably by continuing with the PotD and then... what? All the game content will be already spoiled from September onwards.
Seeing what they're doing with Mario Kart, I can't shake the feeling they're going to send out some free updates and free DLC. So what I think is that the leaked roster could be the final one, but 5 more characters could be revealed after the 3DS version comes out, included in the Wii U version and given as free DLC to 3DS users.
DLC coming later wouldn't surprise me.
Kept you waiting huh?