No one has more likeliness than Lloyd, imo. Cress/Cless is a possibility, and Kratos might make it in if they want Lloyd to be rivaled.
If we start talking about Tales characters on Nintendo systems, then Luke and Asbel are there (Graces was a Wii game first, but Japan only). But I think they have about the same chance as Jude (whose game will be out in NA before this game comes).
So yeah, Lloyd. Cress and Kratos are maybe. Everyone else would be a shock. --- Give the duck a cigar.
In other words, you've played Vesperia. No, Kratos does not appear in any other non-crossover Tales game (and he doesn't even appear in some of the crossovers).
Really, the only Tales character more likely than Lloyd is Cress -- he is the series' original protagonist, he's referenced in nearly every game, and he started on the Super Famicom (for the sake of comparison: both ToP and ToS were ported to Sony consoles, and both received sequels on Nintendo platforms (The first Narikiri Dungeon was not a crossover -- it was a GBC sequel to Phantasia)) --- Series that desperately need another game: LoZ:FS, BoF, Chrono and MM:L (You were so close, my friend!)