Chiaki is pretty great, but I always find myself going towards Akane.
As long as Simon didn't take up the "retro" spot, I'd agree with this. I do think Incineroar is pretty likely, as somewhat boring as that'd be, and I think Geno is pretty likely. After that? Dunno. Shantae's circumstantial evidence is strong, but if she is in, I don't expect her until the very last character reveal.
Akane was pretty cool. Honestly the whole cast was great in D2, really no one I disliked... well HOPE guy got a bit annoying, but that was his thing. D1 had some pretty unlikeable characters, like Kagakure. Never liked him. And also Togami, but again that was kinda his point.
I don't think Sakurai would make a third party the retro character. Retro I assume/feel would be an old nintendo property forgotten through the ages. Like my sig shows(if it decides to show... why does sometimes a signiture on this site shows up and other times it doesn't?) I feel Lip, Ayumi, Mach Rider, and Donbe and Hikari seem like the more likely ones.
And I could see Shantae and the retro being the last unique fighters maybe? that or Geno and the retro, with Shantae and the pokemon revealed beforehand. Plus the echos of course.
I feel still 8-12 feels right. 8 the lowest. That ends us on 80 in the base game, a good number. Uniques would be a pokemon, a retro, Geno, and Shantae(sorry Rhythm Girl :_( ) Echos Would be Ken, Shadow, Dixie, and Medusa.
EDIT: You know... I could see Sakurai or Square making Geno(or any Square rep like dragon quest) as one of the first DLC characters? You could sell that well moreso then a Rhythm Heaven character. Plus I am still a bit sold on my theory that we are getting 3 more unique music icons on the music menu. Shantae, Minecraft stage, and Rhythm Heaven would fit that.