I hope not and it doesn't really make sense... If I buy a game, I want it to be complete. So no Story-DLC, that'd be awful. But even if they release some worlds as DLCs that are not important storywise... Why not keep them for future games? That'd be a complete waste.
Given how nomura talked about DLC and how that leak awhile back kinda came true, there is a possibility of it happening.
What if it were DLC resembling something of a Final Mix version of the game? I'm 100% positive Nomura has that in the back of his mind right now, and it could add more *story cutscenes and innuendos to the next saga in the series.