If that is the case, I would say wait a little while. It is true games slowly advance and need more resources. Watch Dogs is a particularly CPU intense game at the moment and while the 6-core CPUs do a great job of budget gaming they are out performed by the FX 8XXX CPUs and the Intel Core i5 and Core i7 CPUs. Though this is like you mentioned depending on the GPU to a point. If its not fast enough the CPU won't be the problem.
Anyways like I said its best to wait, if you can and don't mind. Intel is coming out with a new CPU architecture called Broadwell. It brings several improvements, faster performance, and greatly reduced power consumption. Its expected to be out by the end of the year, though it could be delayed till Spring, its likely to be out this year though. Motherboards for it are already out. So if you can make do with your current system another month or two chances are you can get a better CPU that will last longer for roughly the same price you would spend now. Its what I would do personally, because even if you don't end up buying one other CPUs will drop in price and you will save money.