There really isn't much point, only a 20-30% increase if you buy the latest and greatest. You have a top-performing CPU already. If you haven't overclocked it you can easily match the performance of any of the non-overclocking i7s.
I upgraded from an i7-950 @ 3.85Ghz to an i7-4770k @ 4.3Ghz, not much noticeable difference in most things. I wanted the intel SATA III controller for my SSDs versus the intel SATA II on my X58 board (the two port marvell SATAIII showed less performance per channel when two drives were hooked up)
Might be worth it to wait for Broadwell, or the chip after that in 2015 which will have yet another new socket.
Quad core with hyperthreading will last a while in the gaming world. You can always invest in a GPU to improve gaming performance. Aren't many games that require as much as an i7 to run well. Keep in mind that game developers almost always target the mid-range consumer to increase their user base. X58 was the premium of 3-4 years ago.
On Tom's hierarchy charts the i7-960 shows up in the second tier. General rule of thumb is to upgrade when you are 4 tiers or more behind.
The only path for upgrade that would make sense would require a new motherboard and processor, and likely you would not notice much difference. What you should tell us is what you use your computer for. It makes a lot of difference in answers to your question.