Hard to forecast the next 4-5 years, by then there could be something which replaces dx12, multicore gpus could be the norm, etc. In terms of gaming, the 4690k is slightly faster by 100mhz at stock base frequency. The 4690k can also be oc'd, which may not seem to matter much at the moment but considering all those who are getting more useful life out of their i5 2500k's by overclocking them the benefits can be seen down the road.
Some recent gaming benchmarks for witcher 3 and gta v. Specifically these two games since they're the latest 'next gen' games actually out at the moment.
http://www.techspot.com/review/1006-the-witcher-3-benchmarks/page5.html...