As I said, unless 6 and 8 core Intel CPUs become common (You can not require hardware that no body has) and Devs force settings that only they can handle, Quad cores are going to be fine for a long time.
A quad core not being able to max a game out does not mean it is not fine.
Thing is, things ar eonly going to get better for PC CPU's over time thanks to new, modern API's like Mantle and DX12 and OpenGL + extensions.
RIght now, a lot of CPU time is eaten up by overhead from the rendering systems. That will go away, leaving behind 4 to 6 cores that are significantly more powerful than what is available on consoles.
If you have to break up a complex set of instructions into 4 millisecond chunks on consoles (ignoring overhead and parallelization/synchronization issues) in 4 milliseconds, on a PS4 you would have solved 6 such intructions.
On a PC, where each of those chunks takes 2 milliseconds, in 4 milliseconds you've solved 8, possibly even more.
I suspect that in the future, the CPU is where PC's will differentiate themselves most from consoles. Last gen it was all about the GPU, as PC GPU's featured more and more advanced GPU based effects. This gen GPU's will coninue to be mroe powerful, push more pixels, etc, but it'll be in CPU intesive tasks that PC will dominate and offer stuff that consoles won't offer until yet another generation reset.