I think a fight with Xehanort's alternate forms would be nice, especially if the Guardian appears and they all have new moves, but technically, even in Days, Sora fought Riku. Roxas is Sora.
Better than just
another Riku vs Sora again in any case, it's getting old.
Roxas himself would slash you apart for that if he heard it, y'know?
Roxas is
not Sora, just as Naminé is not Kairi and Xemnas is not Terra nor Xehanort.
If yensid wants them both to become masters, why would he have them fight eachother? Maybe they will, and maybe they will fight xemnas/XH. Honestly I can see both happening, and both becoming masters, but Nomura said something crazy will happen at the end.
Because people for some odd reason tend to compare this MoM-exam to the
classic version shown by Eraqus in BBS while it is strikingly obvious that Yen Sid does his exams differently.
Furthermore, although I personally don't grasp why, some people seem to want to have a Sora vs Riku again despite we already had it so often.
Nomura always has some surprise up his sleeve, lol.
Like, them both losing and Kairi becoming a Keyblade Master? Now that's fucking crazy.
What the heck has this to do with Kairi?
Both Sora and Riku losing at the final battle but survive can happen without even involving Kairi.
What's wrong with Kairi becoming a Keyblade Master?
The wrong thing is that it is way too early...Kairi has close to no battle experience and progress in fighting abilities.
Not to mention she has no own keyblade.
Making her a fighting machine now would be even more unrealistic than having Xehanort, Ansem SoD and Xemnas around as the triumvirate of horror at the same time.