if you use raytracing over openCL and bulledphysik over openCL you are fine with many tiny cores.
maybe 2000 pieces of 64bit mibs cores big cache is only needed if your ram and ram interface is slow this means you need 512bit ram interface or bigger and XDR2 ram oder gddr5 ram!
in other words: the amd hd7970 is a good gaming cpu if you use raytracing and openCL.
anyway why people still buy normal CPUs? only because the games are using obsolete technique and they are bad designed.