It takes time to come up with whole new card designes. NVIDIA and AMD just released the 280 GTX and 4870X2. And with DX11 around the corner, both manufacturers are probably waiting for the feature set to be "finalised" (unlike DX 10; you can't blame NVIDIA for making a card to spec, then M$ changing what would be required after the fact...).
We know NVIDIA is working on cheaper models of the 280 core, and a new GX2 (2600 GX2?). And we know the 300 series (apparently DX11 capable) is being deisigned. Probably 6-9 months till the 300 core is ready, sooner for other cards.
AMD is busy with the 4000 series, so I would expect the 5000 series to be out in around 6 months.
Also, I doubt even the next generation of cards will be able to handle Crysis at high res. I doubt we're seeing that kind of jump.