Hard to tell from one test of the sort posted, but wow, the high iso looks impressive. It's shocking, but it might actually beat the 5D3 by a good 2/3 of a stop! I'm not sure if it is even possible to build one that would do better without radically different tech. This may be the best we ever get from any standard design. High ISO appears to be insanely good on it. At worst it ties the 5D3/D800/D4 but I think it almost certainly beats them all, some by a margin not even really thought to be entirely realistic. Some insane high iso!
I really don't see the D4 being able to match this level of performance (and it has 2 less MP), although I guess the difference won't be all that large, maybe a solid 1/3 stop behind? (again with 2 less MP though).
(The sad note, for the 5D3 users, is it seems proof that Canon did in fact reserve all of their new sensor fab for the 1DX only and decided to milk the old process one more time for the 5D3 sensor, figuring they could get away with it since they bumped up the body specs so much (but they also bumped up the price so much so.... hmm. Maybe it was all about insuring 5D3 had largest profit margin for a 5 series). Seeing the D800 sensor's quality I wonder if someone in Canon marketing is not ruing their decision.)
(That said the 5D3 is still one of the very best ever at high ISO, if not quite there. At low iso it's a pretty outdated sensor at this point though, at least if you ever shoot scenes with lots of dynamic range.)