People are speculating that the game will be a remake of a previous BN game. While this does sound interesting, there is still a matter of the gameplay. I predict that this would be the perfect time for a game with full 3D graphics like most DS games now days. So then how would battles function? I think it won't be either BN's field or SF's.
Take a look at the 3D battlefield that was made for BN5DS but never used.
If the battles were BN in 3D then which angle would the stage have to be in to play? Remember that the GBA BN games used a perspective that would be impossible in 3D. That would mean any of those stage angles could be used for the game. I hope neither of them get picked because something new could be made that could be better than what we know now.