Kingdom Hearts 4: 12 Disney & Pixar Worlds We Want To See
8. Wreck-It Ralph
The inclusion of Wreck-It Ralph on this list is admittedly a bit of a cheat, as Ralph appeared as a link character in Kingdom Hearts III, so technically he wouldn't be a "new" addition. However, I'm including him anyway simply because of the sheer potential there is behind giving Ralph a full world to play in.
For the sake of keeping it simple the first time around, a world based on Wreck-It Ralph could easily stick to the events of the first film, leaving a future game to adapt Ralph Breaks the Internet. Sora and the gang could turn up in the power strip of Litwak's arcade, only to team up with Ralph as he chases his medal right into Sugar Rush. There, they - along with Vanellope - would inevitably help teach him exactly what being a real hero is all about.
There's just so much to be mined from that first film that it would be disappointing for the franchise to skip it, whether it be having Heartless-corrupted Cy-Bugs to battle, Sugar Rush, Fix-It Felix Jr., and Hero's Duty mini-games to play, or an evil villain to stop in the form of King Candy.