But you missed an important condition: AND there are stocks left to clear.They will if they stop selling and people buy 480s instead
nVidia stopped making 970/980 series cards a while back. They've probably already sold nearly all their inventory to retailers, so there's no need for further cuts to come from nVidia. The retailers on the other hand might need to clear old stock.
Now there are probably all sorts of complicated buy back/discounting credit type things that go on at this and other stages in a product's lifecycle that might mean that retailers could ask nVidia for some credit back on the price they paid for 900 series stock which is now sitting around, which could then be used to help justify cutting their shop prices further. I wouldn't know. But a retailer like OcUK that has a very good relationship with distributors/manufacturers is more likely to bend their ear.