do you believe in 3-4 years from now i7 2600k will have the same performance in games like i7 6 cores cpus?
More aboutgaming performance
Yes because cpu is becoming less needed and the gpu is taking over most of the calculations
They'll perform similar in most games, I doubt we'll see wide spread multithreading in games that can utilize 6+ cores making Sandy Bridge E any faster than Sandy Bridge. By the time that 6 core cpu can perform better, there will surely be a new cheap alternative that out performs both of them.
You can always upgrade to ivybridge next year because it will use the same cpu socket