*answers the initial question*

Well, yeah, wouldn't she have to be? Unless there's like, more than just Rinoa as a Sorceress at that point...which...

Then I suppose she'd just have to be, if Rinoa was the only one left who's a Sorceress, and it just gets passed down through time, it'd have to hit Ulti eventually.

Well, does it really matter all that much? Ah well, this is alot better than those godawful "OMG Rinoa must be Ultimecia!" theories.