Another thought I had in a previous 'possible sequel' discussion was

A: Esthar si, as far as we know, still overrun by the monsters of the Moon right? Those were enough to wipe out the Cetra civilization, so Esthar itself may be in serious jeopardy.

B: Galbadia: All the stuff MUST have weakened them, and pissed a whole lot of countries off. So there just might be more war on the horizon. Who isin charge now? General Caraway seems a likely canidate.

(these things are of course possibly in the past already if the game starts off 'years after')

There's also a connection I guess between the Sorcerss, Hyne (Sorceress being half his power) The Moon, monsters and Guardian Forces.

Also, for an eeeevil plan. IIRC Hyne, way back in mythlogical past, demanded humanity to give up their children. As Squall and co. already HAVE saved space and time, in the sequel, maybe you can go for something objectivel smaller, but eotionally closer like 'the children'?

Hyne would be a fun end-boss though!