There is some good news in the original source, about the GPU power:
"So, what is the XBox Next? SemiAccurate has been saying for a while that all signs were pointing toward a PowerPC, specifically an IBM Power-EN variant. The dark horse was an x86 CPU, but it was a long shot. It looks like the long shot came through, moles are now openly talking about AMD x86 CPU cores and more surprisingly, a newer than expected GPU. How new? HD7000 series, or at least a variant of the GCN cores, heavily tweaked by Microsoft for their specific needs."
Although even an imbecil should have known the GPU wouldn't be based on the 6000 series. Obviously it was going to be based on the Radeon 7000-series (probably with features from the future 8-series).
My bet is that the GPU in Nextbox will be equivalent in power to a Radeon 7850, around the same flops (around 1.8-2 Tflops I think) and amount of transistors, but less power hungry and obviously less focused on compute tasks.
This all in all would mean the Nextbox will be 8 times faster than a X360 and 3 times faster than a Wii U.