There is already a rumor of a 8970 refresh, ready for Kepler.
I found it HERE
The 2nd generation Graphic Core Next architecture is rumored to improve in the number of Stream Processors ( increased to 2304SPs ) faster Core Clock of 1225MHz and increased Memory Bandwidth but with a possible release date of this year!
If you read the thread, this is why the 7970s overclock so well. Could also explain Sapphire's leaked paper.