What if...

They made a Kingdom Hearts version of Dissidia? For me that would be epic. In fact the funny thing is, Dissidia was originally meant to be a Kingdom Hearts game, but that idea was scrapped and instead was made to be Final Fantasy game. Let's take a look shall we:

Character Roster:
-Sora
-Riku
-Terra
-Aqua
-Ven
-All the Organization XIII members

• Xemnas
• Marluxia
• Saix
• Axel
• Roxas
• Zexion
• Larxene
• Lexaeus
• Xaldin
• Xigbar 
• Vexen (ehhhh...)
• Demyx
• Luxord
• Xion

-Old Man Xehanort

-Eraqus

-Vanitas

-Terranort (well, this one's questionable but not entirely impossible)

-Ansem Seeker of Darkness (AKA Terranort's Heartless)

Stages:

-Every single world to have graced the KH series up to this point. (I'd be damned to try to remember em all)

We've seen Squeenix turn generic characters in to full-fledged, eye-candy combatants in Dissidia, So there's no excuse as to why this game wouldn't work. Hell, I can even imagine what some character's EX Mode and EX Burst would be like right now, so Square I urge you to make this game happen.

PS. Sorry that the pictures aren't in proper order. Also, sorry for people who don't really understand the KH series. I would put Kairi on this list, but the problem with that is the fact that she's not too much of fighter, we only see her killing shadows in one cutscene with below novice level fight prowess, but hey maybe Square can think of something Iono.