How "final" is the Final in Final Fantasy?

The third volume of Final Fantasy XIII, Lightning Returns, is just being released by game developer Square Enix. How many gamers pick up on the fact that the word final belies the name of this game?

Game director Motomu Toriyama says Lightning will face her final battle in this version. Should Lightning be worried this means her demise, or can she look forward to a long future of additional final battles? And yes, Final Fantasy XIV is well along in the works. How final is that?