In a recent interview with SiliconEra, Motomu Toriyama, the director of Final Fantasy XIII, revealed some interesting tidbits regarding development and the future of the franchise. The most controversial issue surrounding XIII is the poorer quality Xbox 360 version, at which Toriyama claims it is only a difference in media encoding, and that except for the disc change the two experiences are the same.
When asked about potential downloadable content, Toriyama said that there are no plans for DLC as the game was designed to be a complete experience out of the box. Japanese dubbing, apparently, would require too much data due to lip syncing issues. Future plans include the already-announced MMO Final Fantasy XIV, as well as Versus XIII and Agito XIII, but XV hasn't entered into the planning stages yet. The possibility of future Final Fantasy games being in "true 3D" is something the team is interested in exploring, though it may be left for a future generation of consoles.
Perhaps most interestingly, Toriyama expressed interest in remaking Final Fantasy VII for current-gen consoles. The biggest issue seems to be a lack of manpower and development time, a statement echoed by other Square Enix employees. Yoshinori Kitase has said that it would need to be feasible to have it finished within a year, but that a game of VII's scale would take 3 to 4 times as long to develop as XIII.