fudzilla says the price-cut for GTX 460-1G and GTX 470 is not permanent and will only last until 14th November.
Either their 5x0 successors are closer than we thought, or the cards are too expensive to make to maintain these prices.
We will know in the future if price cuts are permanent or not. There is no way to know. And whether they are too expensive is irrelevant. The question is whether it is good to sell them at this price. The margins might be slimmer, they might even be negative, that does not in and of itself mean they will not continue to sell at the price. The decision will be made based on the economics. And yes selling at a loss can be better than not selling at all sometimes.