Source: GAF
Square Enix recently released the FFXIII Ultimania Omega in Japan. In this extended Ultimania, there are more behind the scenes interviews and discussions with the development team. In the extra section, Toriyama and Kitase discuss something that might be of interest to certain fans.
There was indeed a DLC package planned for the game. It would be an extra area called Seventh Ark, accessed through the third warp gate in Orphan's Cradle. It was going to be an extra area with optional free battles and a quest structure of some sort. There are two screenshots in the book showing the work-in-progress location.
Originally it was intended to be in the game proper, but it was removed when they ran out of time and had to finish the game. After being moved to a DLC package, the team ran into more problems both in terms of quality content and in terms of technical aspects. Since the DLC was not going to live up to expectations, and because there were problems with the differences between the PS3 and 360's download platforms, they eventually cancelled the entire project.
Kitase goes on to say that a sequel to FFXIII is a possibility, but like in the Compilation of FFVII and FFX-2, it will largely depend on the feedback they get from fans of the game. If they feel there is a demand, it could very well happen. He goes on to say that the FFXIII team is already moving on to their next game, because Wada wants each team to be able to steadily release one game every two years from now on.
