What's the motivation behind a $350 Fury/Fury X? Even if 1070 barely beats a Titan X, it should have 20-30% overclocking headroom. I don't think Fury/X would even be good value at $300. Back during 290/290X era, AMD was able to drop prices, those cards had 15-20% OC headroom and same VRAM. This round, 1070 has double the VRAM, half the power usage, even more advanced features/IO, and way bigger overclocking headroom than Fury cards do.
AMD might as well discontinue the Fury line entirely and just price the smaller Polaris 10 8GB chip at $249-299.
They still need to sell current Fury chips, and if Polaris 10 is at MAXIMUM $250, this allows Fury X/Nano to occupy the $300-350 bracket, and offload those chips before the 1070, which IMO they SHOULD be doing now. They should have been fireselling those Fury X/Nano chips before the 1070/1080 announcement to maybe get some people on some "Good deals" of the Nano/Fury X chips that couldn't wait for a 1070/P10.
