I've always been of the mind that Final Fantasy should have it's own "Kingdom Hearts"-type series. Basically, instead of Disney worlds they would be from FFs I - XIII (with certain spinoffs as well) with a new main character and central storyline linking it all (i.e. KH, but no Heartless or Nobodies--something entirely new). And while there aren't as many games as there are Disney movies, the size of each is vastly larger. This means rather than rehashing an entire Disney storyline, they could focus on one thread of a FF story (say, everything surrounding the Opera sequence in FFVI), which would allow S-E to make a sequel sooner than by the time ten or so new FFs come out.
Greatest. Idea. Ever (at least I think so

).