I posted this on another thread but these are my thoughts on the matter.
Before the Ballot was announced, 6 DLC characters were planned (More specifically, Mewtwo & Lucas along with 4 other characters). 2 of the 4 are likely to be Ryu and Roy based on evidence found in the 3DS version and Wolf since he basically owns every poll he's in; whether it be a Japanese poll or a Western poll. The last character is ambiguous because it can be anyone really. Personally, my hope (as well as my prediction) is for this
slot to belong to Solid Snake who's also very missed in the Smash community. I don't really see any other character other than Roy and Wolf (who also have insane amount of support from fans) that is requested as much as Solid Snake.
As for the Ballot, that's going to last until October so whoever wins that ballot won't be implemented until probably the start of 2016 (unless Sakurai gauges what people want beforehand and creates the characters before the ballot ends so that they can be released earlier). My predictions are that K. Rool and Isaac will be the ones
to win the ballot since their basically the 2 most popular choices and also the ones that make the most sense also taken in to consideration that Sakurai won't be making a lot of DLC characters as far as the Ballot is concerned (according to his tweet).
So I think we can very well end up with 8 DLC characters when everything is said and done; Mewtwo, Lucas, Ryu, Roy, Wolf, Solid Snake, Isaac, and K. Rool. Ironically, this actually lines up pretty well with the recent list I did.
(I forget to add Ken in who would be an alt for Ryu here)
The only character that's on this list that I didn't mention before are the Ice Climbers. I have a personal theory that Nintendo will make a push to port SSB4 on the new Nintendo NX console that will be released in 2016 (so I believe) so in order to push the console, they will have a bunch of new modes for the NX version like the Subspace along with an exclusive Nintendo NX character...The Ice Climbers. Would work great to push the console and solve the issue with the IC's not being able to be used on the 3DS. Then again, it's all a theory but it could very well happen.