No Soul Calibur characters, all guests from completely foreign franchises.
Some solid candidates would be:
-Dante or Nero to coincide with DMC5, Nero would be the better fit, but I wouldn't be surprised were it young Dante.
-2B, because people simply won't shut up about her
-Artorias
-While some kind of FF character would be possible, not sure how likely a double-dip is gonna happen considering we just had Noctis in Tekken and Cloud in Smash. Don't think there are many other characters capable of generating that kind of hype, unless we get Sephiroth. I'd be hella into that.
-A League of Legends character would be pretty solid. There's plenty of characters that fit the bill, such as Riven, Fiora, Garen, Darius, etc. The art style would translate well.
For CAS I can guarantee we'll get lots of crossover stuff. Tales of Vesperia is probably a realistic possibility (or just Tales in general). Dark Souls, Code Vein, God Eater, ETC. Be fuckin' ready. Then of course, don't forget about the theme packs. Schoolgirl, Gym, more bikinis than what will already be inlcuded in the base game. I bet we'll get at least three goddamn bikini packs.