Final Fantasy X-3?

[Darth Cid]

I'd say include Shuyin and Lenne, and have Shuyin attempt to atone for his misdeeds in X-2.

Or a prequel of Shuyin and Lenne saving Spira from disaster, the twist ending would have after they do it, the war that separated them happens eventually causing disaster to Spira anyway. I hate X-2, but a prequel like this might interesting imo.