The PS4 is supposed to reach 80-100 Mio. units in lifetime so PS4 would not be a wrong decision. But since the Wii-U is currently running much better in Japan, a multi platform release is also very likely. Nobody knows if the game will ever reach the west but on Sony platforms this will be more likely since Nintendo abandoned the series and chose to translate Bravely Default instead of the 3 3DS Dragon Quest games.