The will be sold B-grade at regular B-grade prices, the 970 value is unchanged as its still a great card. Anyone expecting £100 970's are in dream land, not happening any time soon.
Get some in for the price of your cheapest 960 and we'll talk
Personally, I wouldn't return them, I'd be a bit hacked off over the whole thing, maybe expect a free game code or something as a sweetener, but at the end of the day they still perform great in 99% of scenarios and you can't do that much better for the money.
Each to their own I guess