The only characters that I think have lesser chances of appearing in my opinion are Ashley, Wolf Link and Black Shadow.
I think Ashley (Along with Captain Syrup) is the most logical new Wario rep, Wolf Link could replace Toon Link if they decide to switch him out and use Tetra as the Toon rep and Black Shadow could make it in since he's an F-Zero villain and I think the series deserve a new rep after three games. As much as I like him, Samurai Goroh would be yet another sword user and maybe we could get Black Shadow to have Ganondorf's moveset? I can dream.
Also, I'd rather have Lloyd Irving over Pac-Man, but I think Pac-Man has higher chances.
Edit: More realistic one IMO: http://i.imgur.com/LHcdsPS.png
I prefer Ashley over Krystal, sorry Krystal fans! --- PSN: MounirJemily