I think it could work.
First off, it would be based on an original story, in lieu of rehashing existing storylines.
Secondly, it should owe more to the pre-FF7 years, meaning medieval settings with proto-Industrial Age technology (i.e. airships, et al).
Thirdly, it should be a spectacle. Think "Wicked" or even "Spider-Man: Turn off the Dark".
Finally, the music should be a collabo between Nabuo Uematsu and one or a number of prominent B'way composers. Though the sound should enmesh various genres, like featuring numbers in contemporary styles in tandem with the sound styles of the games.
I've already begun work on a story of sorts, owing to vintage FF. Basically, this young man, the adopted son of a king, finds out that he may be one of the last Avatars, individuals who can essentially meld with Ancients (basically, like Aeons, Eidolons, or Guardian Forces) and bring their powers to Earth. Anyway, he must stop another Avatar from bring forth Ifrit, who here is basically responsible for the Endtimes. And Ifrit can only be kept in check by Aedaa, the Matron of Gaia.
I've also began imagining how various things would look, like Moogles and Chocobos and even Ifrit (it's the same basic means as how they do The Wizard in "Wicked").