I already upgraded last year. I feel like you need a minimum of 8 cores for modern games and apps. You can "get by" with 6 cores but you are bottlenecking your GPU for sure with only 4 cores.
Theres a lot of factors that will determine where the bottleneck is. Can’t say 4 cores will bottleneck a GPU “for sure” without knowing what GPU and what resolution its pushing. When I was running my 3770k with a 1080Ti on a 1440p display, the bottleneck was the CPU in many of the games I play but not all. That system now has a 1060 6gb on a 1080p screen and the bottleneck is almost never the CPU.