My prediction for the ballot is this. Now this is my opinion, so bear with me. A lot of my logic here is by trying to think how Sakurai thinks, and act like he acts. Which isn't possible. Because the man is insane.
I predict a Veteran pack. With classic stages such as FoD and characters such as Wolf, Pichu, some variation of the Icies, and maybe Snake. The veterans chosen may vary of course, but I think they'll want to separate the veterans from the newcomers that are "chosen" (take that word lightly) from the ballot.
For newcomers, I really do not know. Honesty, just judging by the way the man goes back on his word. I think Ridley is a bigger possibility than we think, but I don't necessarily believe it will happen. Other characters that I see as likely might be Paper Mario, Dixie, Shovel Knight (the ONLY Indie character that I think has a remote chance), Tetra (only to promote HW DLC, possibly as some excuse for a Wind Waker anniversary), and some others.