Now, I'm not saying we shouldn't, I'm saying we won't because they always seem to put FF characters in Original world as a replacement 

DI=Spira (Tidus, Wakka)HB/RG=Midgar(Cloud, Aerith, Cid, Yuffie, Sepheroth)Twilight Town=Balam Gardens(Seifer, Fuujin, Raijin)

 

Now there are some exceptions, like YRP being from RG, Selphie being from DI, Leon from RG liek the VII cast, Stzer and Vivi being from Twi.T Auron being in OC (although, since that's where the underworld is and he's dead he could technically be from any world) and Zack being from OC(Hercules style armor) For the most part an FF character is from a certain world that seems to be a KH equivalent to their original home where the other characters from their games live

 

So it's safe to say that if other characters from other FFs appear, Lightning, Snow, Noctis, Stella Vann, Balthier etc. they will either be in an new original world, or added to one of the original world that have been established, but not from the world of their original game.

 

Square may surprise us, but I doubt it, and we will certainly not be seeing the worlds of VII, VIII and X

Edited April 23, 201411 yr by Isamu_Kuno

In my opinion if you want to see a FF world, play that FF game it's from.  They're usually to vast and firetrucking detailed to cram into a tiny piece of KH, especially since a lot as you said have their homes established as KH original worlds in the series.

Well Auron is his original FF version unlike the other FF characters. It's not COMPLETELY out of the picture. I would love to see the turks working as Captain Hooks lackeys.

People want FINAL FANTASY worlds in Kingdom Hearts?

Well , Kingdom Hearts is all about Disney , isn't it ?

And I had the theory that KH3 could have 20worlds split in 13final fantasy/normal and 7disney worlds or backwards.