If it's a game It's not gonna come out until the Osaka team finishes 3D, and I don't think it'll be a main game. It might be a movie. It might be a Reverse Rebirth mode for Aqua. Who knows.
In all honesty i hope it's not a game. As awesome it'd be to play as Aqua in the RoD and as Mickey probably i'd like it to be a movie of some sort.