Ok, Xrd fans seem to notice the Revelator character select, with Johnny and Jack-o as new playables. I'm glad Johnny is back, and Jack-o seems to be pretty cute, and she's also the final spy for That Man. BUT, in the character select, there is one more spot in the bottom right corner, the opposite direction of Faust.
If Baiken is the last character, then Anji Mito would probably be on there too. Dizzy is a Jellyfish pirate and Ky's wife AND the daughter of Justice, which is a bit akward for my taste.
Zappa is clearly going to be the final character, unless there is a new character. OR Chronus, which at the end of Sign's story, he was talking to Faust. Left off with Zappa, his main goal was to find a doctor in XX. Faust was obviously that doctor.
I don't really believe there will be a new character, since Daisuke Ishiwatari himself wanted to bring all of the characters back. So, in my opinion, Zappa would definitely be the final character. (Chronus may be a side character, or a boss)