I just read this on the FFWikia:

quote Kain

Tetsuya Nomura has stated that Kain was considered as a candidate to appear in Dissidia Final Fantasy, either as a secret character or the antagonist representing Final Fantasy IV. He was ultimately excluded, but Tetsuya Nomura has said he personally wanted Kain in the game, and if Dissidia ever has a sequel, Kain is guaranteed to be in it.

It's been stated that there is a very open chance for a sequel! So that means that is Kain is guaranteed as a secret character (highly doubt antagonist, as Golbez is already there), that means there is an opening for all FFs to get a secret character! I vote:

FFI: Red Mage
FFII: Leon
FFIII: Desch
FFIV: Kain (guaranteed, obviously)
FFV: Galuf
FFVI: Celes
FFVII: Zack
FFVIII: Seifer? (he would be a villain, though...why couldn't you have a gunblade, Laguna!?)
FFIX: Blank
FFX: Auron
FFXI: Uh...
FFXII: Basch with secret being Vaan

I would love, and I mean LOVE to see most of these guys in Dissidia action. Leon, Desh, and Blank would simply be sick.

I haven't got the chance to play the other FF series.. so want them to appear in the sequel (if they are planning to make)
FFVII: Vincent Valentine
FFVIII: Laguna Loire
FFXII: Balthier

Go gunslingers!
Of course this is just a wish list..

if they were to do a sequel then it most likely will be psp2/ds2 and possibly iphone.

as far as characters are concerned... my guess would be (at the rate hardware is evolving anyway) that we will see... 3 hero's and 3 villians

good guys i care to think about right now

X/X-2 - Tidus, Yuna, Auron
IIX - Van, Balfier and Ashe

Villians I Care To Think About

X/X-2 - Jecht, Seymore & Shuyian
XII - Gabranth, Vayne, Cid

The new character's would probably be the leading lady in the ff games ex:
FF V:Reina
FF VII: Tifa
FF VIII: Renoa
FF IX: uh... Vivi?
FF X: Yuna
FF XI: Some guy
FF XII: The girl.. was it Asche?
and some FF XIII characters

I know Kain is guaranteed, but I'd also like to see Edge.

the best combination from ff9 besides zidane and kuja is definitely steiner and beatrix

yeah beatrix definetly, garland would be cool too... steiner... meh, vincent would be so BA, as well as tifa, shadow from ff6 pleasseeee, and locke, the girl with pink hair from ff5.. what was her name.. raina? and galuf, pssh i could go on and on and on

they should just work their butts off redesigning every single slightly signifigant character down to biggs and wedge, and have them all as playable fighters in one massive fighting game, put it on the ps3 or a different next gen system, and make it the best fighting game ever ever ever ever.

because it would be.
totally.
but i'm dreaming.

The cast of character seems pretty godo right now. I obviously want them to add more, but if you add one, the fans will expect 10 others who played similar roles.

BTW: I think what Tetsuya Nomura just said was unofficially announcing Dissidia 2. Just my take on things...

Zack could be a pallette swap of Cloud. I would like a gunner like Vincent or Barret and Yuffie because of her shuriken.

quote Muller

Zack could be a pallette swap of Cloud. I would like a gunner like Vincent or Barret and Yuffie because of her shuriken.

Please, no. Zack is not like Cloud's alter ego or something. He's a person who's totally different from Cloud, both looks and personality-wise.

I'd go with..

FFVII: Red XIII
FFVIII: Zell
FFIX: Freya
FFX: Auron (this one comes to mind real easy)
FFXII: Penelo !

I mean like how they use Ken, Ryu and Akuma swaps.

For FFXI add my character into it

^ cute XD,

either way id like to have shaow/locke/celes/ orrrrrrr, leo, for FF6

for 7 zack would be a good addition,