Final Fantasy XIII in a recent RPG Site interview with Squeenix's Motomu Toriyama and Yoshinori Kitase. According to Kitase, the developer is "exploring the option of downloadable content, perhaps adding new areas, items or enemies." He went on to add that any DLC wouldn't expand the game's story -- that'll be completely contained within the core game.
Our hope is, as ever, that any potential expansion for the game will finally add that Final Fantasy kart racer mode we've been waiting on ever since -- wait, they already did one of those? Get out of town!