I think they should do another FF like it in general (per another thread: bring back ATB - plus the classic medieval theme, world map etc) but it should stand on its own merits. IX was great, but also kind of exists as a mish-mash of FFI-FFVI references. We already have one such game, and therefore don't need another.

That or maybe some kind of FFVII-X throwback game for those who loved the Playstation+Sakaguchi era, but cut IX out of it because that would just be references on top of references.