While I feel that VIII has the most potential for sequel material on the basis that its one of the least developed worlds from the modern FF series, I feel that if the Compilation of VII is any indication of how it would be handled then I doubt I would get any of the answers I wanted. Not to mention that Time Travel already is a screwy plot device that mucks up continuity and causes major retcon problems that I feel VIII sequels/prequels would be devastating.

I'd do better with an updated Ultimania that finally gives a detailed explanation for the Centra are, gives a timeline for Laguna's action and maybe a few details about the Sorceress Wars and Ultimecia and her timeline as well.

I don't see how expansions could give me these details without screwing up other details and since VIII already has a shaky plot and story elements, I don't think adding new entries will really help the game so much. Hell, I don't even want a remake cause I just came from an old playthrough of the title and outside of its normal problems, I feel the game has aged rather well which completely surprised me.