Looking beyond the 4870 X2, Nordic Hardware have a few little tidbits of information relating to AMD's plans on its next-gen cards. It was mentioned a short while back that early next year the company hopes to have successfully shrunk things down to 40nm with its mainstream RV740 core, and soon after, its next big bad boy, the RV870.
An initial rumour was going around that RV870 would carry with it 2000 shaders, but the chances of this arn't great as apparently AMD are wanting to take things easy for a little while once 4870 X2 hits town by spending some more time mastering 45nm and further improving on its multi-GPU design.
For this reason, RV870 most likely won't be as big a leap as the one we saw from RV670 to RV770. Thanks for Nordic for the briefing.