You mean like how the GTX580 is still a few percent slower than a 5970? 🙂
The GTX580 *might* be Nvidia's highest end part (unless they do make a dual GF114 part). On the other hand we all know that the 6970 will be the second fastest AMD card.
True, it could shape up that way again.
But if nV can manage two chips on one PCB, they may take back the single-card crown.