1) Gargoyles! Man, that show rocked. We recently got the first two seasons, and it is as great as I remember. Apparently the 3rd season The Goliath Chronicles jumped the shark, so we'll pass on that one. Anyway, I came up with the perfect setting for them too.. The expanded Traverse Town from KH:3D was flipping huge and had lots of high buildings. They'd fit right in. Story wise, they were cursed as they were in the show, then Malificent moves into Castle Wyvern and having partnered with David Xanatos, raises it above the clouds. Due to the enmity with both villains, the gargoyles re-settle in Traverse Town.
2) The Duckverse... you know, Ducktales and Darkwing Duck. Scrooge, Donald, and the nephews are in, so... I want to see Scrooges Moneybin as a minigame, Launchpad and perhaps Gizmoduck to make appearances. Original (living) voice talents, of course.
3) Max (Goofy's son). What ever happened to Goofy's wife anyway? Do I want to know? Anyhoo, since Pete is in already, where's his son.... what's his name... PJ?
4) If they include Star Wars... and let's face it, they will.... the Death Star world, set in Episode IV. Luke joins you... get the original talent out to record voices. However, since The Force Awakens has come about, it'll probably be that one, which I know nothing about (at the time of posting).
5) If they include Marvel, and they will... Wolverine joins your party... and maybe set in Genosha or something... battle Magneto (I'm curious if his powers would effect the keyblade). Edit (2015): Since X-men has been out of the spotlight for a while (oh... no I haven't seen Days of Future Past) it would more likely be an Avengers setting. Edit 2 (2016): Since Marvel doesn't own the license for the X-Men films, and it's doubtful they'd be allowed to use it in another medium, so just forget the X-men thing and assume they'd use Avengers for now.
6) If they use Pixar stuff.... oh boy... that's a whole other multiverse of possibilities, but personally I'd be content with just a Toy Story world. Wouldn't that be great!? Sora and Co. turned into toys... exploring the houses and yards of Cid and the good kid I'm too lazy to look up but ironically it's more work to type all this that to break down and check wikipedia *gasp* and breathe...
7) A studio Ghibli world would be excellent... I recommend Howl's Moving Castle.
8) It should go without saying that Castle Oblivion will return for... reasons... which are spoilers.
9) Another Final Fantasy world - Radiant Garden clearly isn't FF7/8 world and the Destiny Isles clearly aren't in Spira/FF8 World. Seifer & Co. appeared in Twilight town... do they know Leon in this continuity? Setzer appeared once... where's he from? I could do with more FF6 characters. When it comes down to it though. if they take a straight world let it be Final Fantasy 6, with at least Terra, Locke, Edgar, Sabin, and of course Kefka!
10) We saw Big Hero 6... so, now I want... no, demand to be able to visit Sanfrancokyo, have Sora meet up with this near-clone Hiro, and team with Baymax.
and just cause it's funny...
X) Gummi Bears! So it won't happen... I still get a chuckle out of the thought. I mean... where did those gummi blocks come from in the first two games anyway?
Return of the Riku Replica (from KH:COM). The chronicle of COM in 3D alludes to the possibility, saying the replica "seemingly vanished". Yup. He'll be back.
Master Eraqus - Sora revives hearts and such. I expect it.
Data Sora - Though he was a construct of Sora as computer data, he was his own character with his own experiences, a trait demonstrated by the series to be important.
DiZ (Ansem the Wise) if only for the epic voice of Christopher Lee. Edit (6/16/15): Dang it... he's departed. Ian McKellen, maybe? Who CAN fill his shoes?
Rescue Rangers - Put Chip and Dale in their outfits from the show and add Monty and Gadget to the mix, why not?
Gaston - Isn't it weird that though Beast's Castle appears in two games, Gaston doesn't even get a mention? For that matter what about Belle's father? Really... we need a chance to beat Gaston's frenchy arse! Of course... during the credits of KH2 we see the curse on the Beast was broken... so le sigh.
Rinoa - Squall... err... Leon gets a letter from her during the credits of KH2. I think it's inevitable. What's their story in this continuity?
Phineas and Ferb - Traveling the worlds by their own means (of course Candace plans on busting them for it), Sora and Co. meet them occasionally. A subplot with Doofenshmirtz and his Inators would be great... and obtain Perry the Platapus as a summon. Start the animation with P&F (on a random world each time) saying "Where's Perry?" and then cut back to him assisting in the battle.
Guardians of the Galaxy - This group is another that would travel the worlds by their own ship. No idea what they'd do exactly, but it'd be wonderful and epic. Groot summon!
Princess & the Frog, Finding Nemo, Tangled (confirmed), Cars, Monsters Inc., Wreck it Ralph (summon please... "I'm Gonna Wreck It!"), Frozen (...), Brave
Pocahontas, Brother Bear, Song of the South, Chicken Little, Brave Little Toaster
Twilight Town E3 2015 Trailer
Mt. Olympus E3 2015 Trailer
Big Hero 6!!!!!! Announcement