Forbidden Mountain
Perhaps I'm biased because Sleeping Beauty is my favourite Disney film and Maleficent is probably my all-time favourite character, but exploring her castle made me very happy in Birth by Sleep. Maleficent has appeared to be a recurring central antagonist but I don't feel like we battle her as often as would be expected. From the Secret Reports in Kingdom Hearts III and her appearances in Unionχ I believe she is going to play a heavier role in the plot and will help to connect the current story with the Lost Masters. I think it would be fun to challenge her again in her Forbidden Mountain, but with her stronghold having taken on the form of the Castle that Never Was, which she hoped to take over in Kingdom Hearts II
Possible bosses:
- Maleficent
- Dragon Maleficent
- Pete
- The Goons
The Arcade
Although I'm not a huge Wreck-It Ralph fan, his Arcade would be an ideal minigame world. Sora knows Ralph through summoning, so they wouldn't require a large introduction to one another, and playing in this world would help Sora to Reconnect with older friends from other worlds, some of which he felt he has a weakened bond with (like Pooh). There is also potential here for some fun cameos without them feeling tacked on to the story for the sake of it.
Hunting Woods
This is perhaps another one of my biases because I adore The Fox & The Hound, but I think the woodland from that film and its themes would be a suitable circumstantial world in Kingdom Hearts, particularly as Sora progresses through his adolescence. He and adolescent Todd (acting like a Dream Eater) could pursue one of Sora's old friends-turned-enemies, accompanied by adolescent Copper. Riku immediately comes to mind, but I wouldn't want to risk tarnishing their relationship or Riku's character, so perhaps Roxas, Xion, Neku, or even Kairi would be a suitable opponent. This would be an effective way of showing Sora that time has a way of changing things.
Possible bosses:
- Riku/Roxas/Xion/Neku/Kairi
- Copper
- Nightmare Chief
The Anthill
This would be an interesting world to explore, particularly for those of us who played A Bug's Life on the PlayStation, Nintendo 64 or PC. With Sora's clothes, he would become antlike and smaller so he can see the world differently, and it would be interesting to watch him engage with Flik as he's being lambasted for the Warrior Bug fiasco, and act as a Warrior Bug himself. Towards the end of Kingdom Hearts III I felt like Sora was beginning to unintentionally get somewhat arrogant, insisting that he take on Master Xehanort alone (I know that Kingdom Hearts was a greater threat). The world of A Bug's Life would help him to understand that though he gets his strength from his friends, he needs to trust the strength of his friends too. Plus we get to see Ant Sora!
Potential bosses:
- P.T. Flea's Circus
- Hopper
- Thumper
- Early Bird
The Future
This would mainly be ideal due to the series' current emphasis on time-travel and foretelling. I think it would be interesting if Sora was taken to a world beyond the Master of Masters' gazing eye, the world of Meet the Robinsons which bathes in light. I think this world could be quite an interesting plot device if Sora finds out about the Book of Prophecies, and despairs as a result. Perhaps by losing his heart and travelling to a futuristic time to another version of himself, or by finding an alternative method of time-travel (Cornelius' time machine) he could travel to the future, or even just a possible future (so that the final battle still feels like there are stakes). Knowing Nomura, I could see him actually introducing Future Sleeping Worlds as alternative timelines. Seeing how the world may turn out, this would reinvigorate him for the final battle with the Master of Masters (assuming that's where Nomura is going). We could even see the future version of Sora crippled, or reclusive, due to the final battle, and Sora must decide if he wants to make that sacrifice to protect the light.
Potential bosses:
- Tiny / Giant Tyranto Rex
- Frankie / Frog Prince
- DOR-15
The Death Star
Venturing beyond the Outer Realms, the Galactic Empire has noticed a huge imbalance between the light and dark sides of the force and has gone to investigate. Not expecting the Death Star to be where it is, Sora flies the Gummi Ship nearby and is drawn inside. This world is pure fanservice, but could enlighten us as to our understandings of the forces of light and darkness, and confirm Xehanort's theory that both should exist and be controlled in equilibrium.
Potential bosses:
- AT-ST
- Lord Vader
- Emperor Palpatine
- Death Star