Although Umatate didn't say as much, there's little doubt that this future model would be an answer to Sony's A9. Simply speaking, Sony is still thrashing Nikon (and Canon, for that matter) in the mirrorless market, if not interchangeable lens cameras as a whole. A parallel to the D5 could prevent pro photographers from switching to Sony. And for Nikon, that's critical. Camera platform switches are expensive by their nature (the lenses are seldom cheap), and it could be that much costlier for Nikon to win people back.