Depends on your refresh rate simply put. At higher refresh rates, CPU needs to prepare more frames (for similar games) in turn which means a higher CPU load. 8700k comes into its own here. For 60hz panel however, those CPUs (basing the 2700x on the 1700x) would be fine for it.
If your using a 4k panel which you are from your suggestion, would not bother to move platforms, CPU will be fine to get 60hz in most games and the limiation will be the 1080Ti in demanding games at that resolution.
If your using a 4k panel which you are from your suggestion, would not bother to move platforms, CPU will be fine to get 60hz in most games and the limiation will be the 1080Ti in demanding games at that resolution.