Warning, probably LOTS of spoilers involved:

Yes but all the FF's have one underlying theme: finalizing a previous defeat of evil or stopping an evil from resurging. With I, it was an actual temporal loop. II and III have more subtle themes, but stopping a problem from deep in the past from happening again runs through them, such as III's stopping the darkness from surging again like light had in the past. IV stopps the lunarian rebel from trying to take over earth again, V stops the last weapon on an evil euno from destroying everything and destroying him rather than resealing him. VI is obvious, it's loop is explicitly told in the prologue. VII is clear cut: stop jenova from destroying man like he killed the Cetera. VIII has more time loop stuff, and IX has one more of those less pronounced themes. Is this theme present in XI? that's what makes it an FF or not. I am also concerned still on how it will keep for posterity if it is an online game. The online service can't last forever, then the game is dead, is it not? And one trivial question. The normal battle theme in FF's I - VI and IX have all been varients on the same basic theme. Is there such a varient music in XI, or did it go the way of VII and VIII?