this is old news. the fatal flaw to the concept is the combined power draw of a CPU and GPU on a single die could be just about crippling for the motherboard's electrical traces and the heat output would be far too high. furthermore the issue of memory bandwidth poses a problem. i'm sure everyone has noticed the difference in GDDR and DDR frequencies. integrating the GPU to the CPU would mean it needs to access system memory. hello bottleneck. so for it to be worth it we would need to either have motherboards which have integrated memory for use by the GPU or motherboards with seperate slots for GPU and system memory, also introducing a new memory standard for the second set of slots. it would also have very poor upgradeability and a bunch of other drawbacks.
if anyone is interested in reading a fairly in depth discussion on it you can sign up to this forum to read (it only allows members to view threads).
the threads about a month old