It was inevitable. The Nikon D4 has spawned its follow-up, the Nikon D4S, as seen at the Consumer Electronics Show 2014.But there's a small problem: it's a mock up that's tucked away behind glass and there's no official spec as yet. What we can tell you with confidence is that it looks identical to the Nikon D4, as these pictures show. Well, with the exception of that all-important "S" designation on the name.So what do we anticipate to be new? If the update from D3 to D3S was anything to go by then we should expect much the same here: new sensor technology and, we would think, a jump from Expeed 3 to Expeed 4 processor.That, in turn, should mean an even more significant speed for churning through long bursts of shots. Whether it will be faster than the 11 frames per second of the D4 is unknown, but not an impossibility. Otherwise it's all a bit of a mystery. Is Nikon outing the concept now ahead of the Photokina show in September of this year, or will we see the D4S surface sooner?