It would barely be faster than the hd7970, a larger chip, and wouldn't be out until some time after the hd7970. It would hardly be exciting, unless it was priced ridiculously low.
I dont know what benchmarks you are looking at. But the anandtech review put the 7970 about midway between the 580 and 590 on most benchmarks. I would hardly call outperforming your competition by 20-30% and nearly doubling the performance of your previous generations single GPU a failure.
I dont know why people create such lofty and unrealistic expectations for GPUs.