Don't get me wrong, I really dug the story concept for Dissidia, however I don't really want to see it used again.
I want a war scaled conflict between multiple battling factions, preferably 3.
And forget the whole 'one villain, one hero' from each game, they should get a large number of them, as many as they feel, and create an entire world where all of these characters fit in.
And, in order to keep the story as massive as they can, to include all characters, move it onto the console instead of the PSP.
Characters that should be involved include, but are not limited to, the following.
FF I
Warrior of LIght
Red Mage
Garland
FF II
Firion
Maria
Emperor
FF III
Cloud of Darkness
Onion Kid
FF IV
Cecil
Edge
Kain
Edward
Golbez
Zemus
Dark Elf
Rubicant
Scarmiglion
FF V
Bartz
Ex-Death
Gilgamesh
FF VI
Terra
Edgar
Sabin
Umaro
Mog
Setzer
Strago
Shadow
Cyan
Kefka
Ultros
Seigfried
Leo
FF VII
Cloud
Tifa
Cid
Sephiroth
Hojo
Reno
FF VIII
Cloud
Zell
Ultimecia
Seifer
FF IX
Zidane
Vivi
Amarant
Freya
Kuja
Garland
Lani
FF X
Auron
Tidus
Jecht
Symore
FF XII
Bausch
Balthier
Vayne
Gabranth
FF XIII
Lightning
Sahz
Snow
Cid Raines
Jihl Nabaat
FF Tactics
Ramza
Agrias
Delta
Gafgorion
What their goals are, and how exactly you would play through the story, I don't know. I don't know if I'd rather have one solid story line, or a story that changes based on the side you play as.
I might add more conjecture later, though this thread is for everything you'd like to see in a new Dissidia game, not just discussing my random drivel. ;p