ATI has to win with the 6900s. A slower card means their refresh yielded less performance than Nvidia.
Releasing a product last is usually a guaranteed win. If the GTX 570 keeps up with a 6970 it would be a disaster.
For the future of the industry, I would like to see the 6970 beat the GTX 580. It's still quiet from AMD though.
Well, the 6970 was intended to beat the 480, so I doubt it will be wrestling with the 570, since that would make little sense.