That expensive? When 360 came out it had a top of the line gpu in it.
Also, its not like they're going to use a real pc gpu and put it inside the console just like that. By 2014, there will be new tech available
PS4 will suposedly be out in late 2013 or early 2014. Most of the hardware is already locked in. Same goes for X720, dont expect wonders.
X720 will in addition of gaming separate a large chunk of its hardware for Kinect2 [4 player body tracking, finger tracking and who knows what more].