Depends, Some games are more Dependent on the GPU than CPU i.e BF3 & probably BF4. GT5 i believe is CPU intensive, not to sure.
For all games to utilize more than 4 cores, i'd say maybe another 1 year at minimum. Next Gen Consoles are pretty powerful, I think they are rumored to have 8 cores, so games with be optimized to run on the PS4 & Xboxone with PC as second thought unless it's a PC exclusive game i.e WoW.