Originally Posted by Stingray 
True, but they also said "We’ve done a number of tests and the 2D/3D mix feels very natural." If the art was just being done in 3D for convenience, but would be served up as 2D frames in the final product, I don't see why they would say that.
There's no way of knowing what their definition of "2D/3D mix" is until we see it.