Right now for games it would be very hard to beat the Intel® Core™ i5-2500K as the best processor for gaming. The issue is that very few games can take advantage of more then 4 threads and those that do yield very small improvements for additional cores/threads (you may get a % point or two).
Now in order for this to change something would have to happen in the compiler/programing front that makes it a great deal easier to add additional threads to the multi-threading support on the program. I have a friend that is a Ruby programer and he hates trying to program anything multi-threaded let allow trying get support for 4 or more threads out of it.
So while anything could change I don't think that the investment in the Intel Core i5-2500K could lead you wrong for gaming.
Intel Enthusiast Team