hate to break it to you, but the GPUs inside the next Xbox and Playstation are already old. They are likely going to be from the AMD 6xxx series, which launched back in 2010. The next generation of consoles is already behind most current mid-range PCs.
The Xenon which is used by the 360 is very old but the 360 is still capable of running games with good looking graphics. Take Skyrim, yes the P.C version is nicer but it's not by any stretch of the imagination thaaaaaat much better.
If the next gen does use the high end 6XXX then it will have 2 of them and like most hardware, the software usually catches up later on. It will also have 16 core processors. Consoles aren't there to compete with P.C's, they are a seperate entity. To be honest, there are some beautiful graphics on the 360 at the moment and the Xenon is around 3 years older than the 6xxx.
My Galaxy Note is quite old now but there isn't the software to push it to it's full capability, it does the same as the S3.
You dig? And man (xbox) can't live on bread (amd 6xxx) alone.