You might know that a few 10.5mm DX lenses have been modified to work on FX. But most people would properly stay away from getting going with a hacksaw on their brand new lens
So why could Nikon not just change the lens slightly to make it FX compliant. It would be very easy, the lens hoot have to change from a permanent design to one that can be removed or slide back. Now you have 2 great lenses in one, incl 220 degree fisheye on your FX camera
Nikon properly wont so if I get one and move to FX, the hacksaw would have to get into action
Pete