Nah not with 55nm g200 chips. They wont produce that much heat. Considering the 4870 ran hotter and an X2 was made id presume a 55nm GX2 would be cooler than the current 4870X2. Then again, they could use that extra thermal leeway to OC the
Just like to say that the R700 although doing well in current gaming standards shows NO headroom for ability, even when using the physics subset to parallel graphics. The GTX280 has only "scratched" its potential (around 15% as quoted by a friend designing real-time raytracing with the CUDA system embedded in nVidia systems of late).
Its cheap and works well so good for them but to say it is more powerful can only be viewed as outright lunacy by anyone with a grasp of the graphics full potential from within the industry.
Edit:
Forgot to say that you can freely contact the chap on the UKCS forum as I have mentioned here before.
It would be nice to see the lowly 4850 topple the GTX280 but I just can't see it happening, and even if it does nVidia will slash prices to keep a foot hold, which tbh I am surprised they have not yet done. And when things settle down Intel will shows its face