I've seen that same photo, but people are claiming, not me, that the canon requires a slower shutter speed to match the D4 at the same iso/fstop. I dono.
Anyways, I'm saying that OTHER people are saying that the D800 will match the D4 when the images are both 16mp.
Personally from what I've seen and my uses, it should be enough, and I don't have to sell lots of lenses, however if the D4 magiclly turned in to the D800 I wouldn't be upset.
Edit:
What I would like to see are testshots like that photo, with the 5dM3, D4 and D800, all right next to eachother at 16mp, which don't seem to exist.