Hmm, if I had to select merely three, then they would be:
Lilo & Stitch - HAWAII:
Its incorporation is a no-brainer. Firstly, its potential is perpetual: Visiting a tropical area similar to Destiny Islands, Jumba & Reuben creating banter with Sora, Donald & Goofy and Aqua, Ventus and Terra reuniting with Stitch after a multitude of years! The opportunity to include this world will not be missed as they have rightfully set it up in BBS.
The Jungle Book - Deep Jungle 2?
I believe that this elusive world will finally find its place inside of Kingdom Hearts 3 - like Toy Story. My hypothesis to the reason that it has yet to be include is that in KH1, during the planning stage, they had contemplated including it but opted to use Tarzan instead due to its relevance - and that they did not want to jungle worlds in the game. Moreover, in BBS, I believe that they scrapped it because it was too reminiscent of Deep Jungle in KH1; heeding the fan's backlash, they deemed that they have a sufficient number of worlds and it would drag the game on too long (two other reasons could be: its vibe was too similar to Neverland's, or time constraint). Hence, I believe that with KH3 open world gameplay, they will finally give us The Jungle Book. Additionally, we need Baloo and Sora, Donald & Goofy singing 'the bare necessities' together in a cutscene.
Frozen - Arendelle:
Advertisement, nuff said...:wink:
Nope, I believe that the reason it will included is due to its sheer uniqueness: how could Square pass the offer to include a world centred around ICE? Where else are they going to get this opportunity? Additionally, due to its relevance, world size, boss opportunities and 'love and family' focus, I believe that this world is a shoe-in for KH3.