I can't see MS using a graphics card (sea islands) that isn't' even out yet in a brand new box. The yields would be too low and cost significantly too high. That part simply makes no logical sense and has to be BS.
8GB memory could be right on a dev unit and then the retail unit having 4GB or 6GB. neXtBox will likely have a good amount as the OS will be windows 8 and on PCs that requires 2GB alone. Then have it reduced due to neXtBox being more streamlined and increased due to the likelihood of an enhanced Kinect. However, it still is on the high side and likely will end up with the most logical of 4GB max with ~2GB for games and 2GB for OS/Kinect or something similar.
The CPU... idk. A lot of play room there. However, the original rumor when it switched to AMD was that it was going with the next high-end APU (same as Sony).
However, there has been a more recent rumor that stated MS had to push back initial plans as they had issues with yields in their new CPU/GPU. That would make sense if it is technically a 2013 model based APU, i.e. the Steamroller series that then matches the general layout of this rumor.
Hmmm... I still think the 2013 chips will have too much cost, heat, and power usage to be put in any console.