At this point, my predictions are twofold:
If it turns out that we really only have four characters left, then I’m going with Geno up next, a “wild card” slot that could be Capcom, Namco, or Ryu, Crash, and finally Chief. Even with the other Microsoft rep in the pass, the idea of having a full-on mascot fight between Mario, Sonic, Crash, and Chief seems like something they legitimately might not want to pass up, plus the inevitable “Finishes the Fighters Pass!” splash screen pun.
If we get the four extras as well, then I’m not sure of placement overall, but: Geno, Capcom, Namco, Ryu, Crash, Chief, and two more first-parties.
Either way, I’m really quite confident in Geno being #8. I know that some might think that he wouldn’t really be a “popular” TGA reveal, but if the Mario RPG remake/sequel rumors are true, then I could see it being tied with that for a bit of a larger reveal.