My 9x 1060 3G (Micron) makes 64 at 70W each (stable over long time, 125 core 1350 memory). They made 74 at 90W when tested.
Running at 60W each was not that stable.

Profit after power is very important now so making the most/W is the game. If you need twice the power per hash with a 580 compared to a 1060, the AMD cards will start to be landfill material, since total profits will not increase.