This won't pane out to be too bad for AMD. I'd say way less brand damage than the 970 3.5 gb issue.
So 3 % more if correct in some games that are going to be reviewed vs the 1060 . So the gap is reducing already. Performance per watt increases are already occurring through drivers - nice to see its this soon too thanks to the media making lots of noise about it. I guess 480 owners are getting some benefit from this non issue publicity already.
If you have a extremely crappy low end psu then you can tick compatibility mode to be sure you are ok , most people will not need to bother. I'd be surprised if this actually reduces performance much at all . Could improve performance for some ref cards if its undervolting as has been proven on numerous sites already.
Damaging sales ? last i read it was sold out everywhere ... doubt it.
i7 930 @ 4.75 -> i7 2700k @ 5.45 -> 3770k @ 5.2 -> 4820k @ 5.1 -> 5820k @ 5.3ghz