I think you are not factoring in the cost of FPGAs.
That's a good point, but the FPGA market looks totally dis-functional to me. I suspect that pricing practices will change as the impact of the Intel/Altera acquisition works thru the system.
ASICs will continue to dominate mining and GPU miners are very resilient. But for FPGAs, even without their magical powers, will still remain a viable alternative for some people.