The expanse of the Final Mixes vary quite a bit so I honestly don't know how much we can expect. There are rumors on the Forum that a some ideas and stuff were scraped because of disc space, so maybe a few of these things were already planned. but not able to make it into the final game, which means their inclusion in a years worth of work on a FM wouldn't be unlikely.
Here's my wish list, most of which has already been brought up by others.I'm going to try and group them in major and minor changes.
Minor changes
- An option to ask Merlin about Kairi & Axel's training. You'd think that Sora would be curious about that, he didn't hear from Kairi since starting the exam, if I'm not mistaking. This would also show she's on his mind.
- Objectives like in 0.2
- The option to turn off Attraction flows
- More banter and dialog while exploring the worlds
- A chance to get selfies and talk to every other Guardian of Light, like in KH2 as Audo mentioned, it is weird that when you return to the Keyblade Graveyard from Scala they're all gone.
- Expansion to the Keyblade Graveyard, more cutscenes to explain what's going on and why everything repeated itself after Sora saved everyone. Maybe give Ven, Mickey, Axel, Aqua and Kairi moments to shine?
- Access to Elsa's Ice palace. It's on the Map why can't we get in there.
Major changes
- Expanded Riku Scenario, mostly the Realm of Darkness, though some exploring of Radiant Gardin. It's seems odd to make Riku playable only for a fight or two.
- Maybe a Kairi Scenario or at least more cutscenes of her and Axel's training
- Expanded Gummiphone let us call others and get calls ourselves, maybe even use this to get updates on the replica from Ienzo or other minor plot updates.
- Option to Fight as Riku or Aqua in their respective Keyblade Graveyard battles.
- Maybe give us one more fight along side Kairi and Lea, seeing their's was cut short
- Tournaments ala Olympus Coliseum or Mirage Arena in previous games
- Ability to repeat or revisit boss fights + more battle gates. Maybe accessible in a dungeon like in KH2?
- Secret episode where you as Sora go and save Kairi.