To be brutally honest... Ninja in Final Fantasy XI was originally planned by the Development Team to be a DPS Class. The problem, and reason why it was regarded as a Tank was because the Devs decided to give Ninja the broken-est version of the Blink-Spell they possibly could, and allowed the players to give Ninja access to the Warrior's Provoke Command via Sub-Classing. That is the only reason it could tank. Otherwise it was really just a really bad DPS class.

Will it be a Tank in this game? Probably not. Will it be a decent to good DPS class? Who can tell other than the Dev's at this point?