ati had to do alot of binning to get chips to make the cut to be put on the 5970, look at how much more energy efficient each 5870 core must be to be considered a hemlock, 30%? some lightning 5870's are reaching 1500mhz, ln2 sure but think about the capabilities of the yeilds of the past month let alone 3-4 months ago.
with the current stats of the gtx 480, nvidia has alot of work to do before they can even think of releasing a dual fermi part each with 512 shader cores, the heat, . . . the wattage, . . . getting two fermi chips with all of thier cores, . . . 3 massive hurdles, yeah they said they want to do it but how long,
i would be suprised to see such a card before december.
5xxx line is more than a 4xxx with a sticker its actually an evolved design.
also i cant state how meaningless i feel tech demo's are, first of all they are incredibly inefficient for how good they look, thier are plenty of games released, that not only look better than many 3d marks, but perform better, by the time games use the amount of tesselation as the dragon demo developers will be much more skilled than the first ever small team that made that poor demo, so in 6 months, a 5870 will still be playing games with dx11 features.
the 5870 in its stock 1gb form is currently held back more by memory and clock speeds not the actual architecture.
the current 5870 design loves higher memory clocks, the overclocking scalability is pretty much as good as it gets.
i see a 2gb 5870/5890 clocked at 1200mhz gpu 6000mhz memory not only an easy possibility but highly likely,
ati knew what it was doing when it was designing the 5870 gpu.