well it could affect the 1070 even though they are not in the same segement they are close enough to sway potential customers, but still question of the 480 performance that will decide at what degree.
1080 wont sell as good as the 980ti or 780ti, a lot of enthusiasts see performance not good enough to upgrade.
last would be stock AMD only produces 100+200mm² chips, with no pro cards in sight, they can have enough stock to satisfy the demand, that will be huge in my opinion, everyone is tired of 28nm and want to get to the new finfet.
i think nvidia might have a problem with stock, they started with gp 104 at 300mm², and they will have to compete with polaris 10 & 11, i think gp106 200mm² will be competing with polaris 10, and they will still need a smaller chip to compete with polaris 11 in 100mm² size, because cutdown gp 106 wont be as cheap as a 100mm², so nvidia might end up with 300+200+100mm² production (excluding gp100 with 600mm² that they can delay i guess), against AMD's 200+100mm², that is half the wafer production, and better yields at lower size, more cost effective, i think 1080/1070 will have stock shirtage quite often, and nvidia will focus on 1060/1050 if they want to keep the prices down.
both vendors should start Vega/gp 102 400mm² chip around end of Q3.