I would say, wait until you know that you need an upgrade, not just do it because "what if new games don't run well"
So far all that has been out is a beta of battlefield 4 that is running badly in all systems, you can't base a decision just on that. Nobody knows if new games will need 8 cores to run, most likely they will not need them, is hard to program in multiple threads, and most companies just won't try to do it. --- Mystery is the source of all true science.
I'd say you're pretty good for another year at least with that hardware.
You could always get an SSD or a 1440p monitor, as both of these things make every aspect of using your machine more pleasant. --- Intel i5 4670K | Corsair 16GB DDR3 | Gigabyte GTX 770 4GB | ASUS 27" 1440p Corsair 480GB SSD | WD 4TB HDD | Fractal Design R4 | Corsair 750MX | Win7Ult 64