If you go the "waiting" route you will be waiting forever. There will be a Ryzen 2 after coffee lake, GTX 2060, Milk Lake(fictional), etc.
7700k as you already pointed out is for pure gaming preferably with no background tasks running. The online benchmarks are all on a clean install of windows and only the game running. If you stream or record on CPU or basically do anything other than running the game during your gaming, you will need at least 6 cores for that.
R5 1700 would be the sweet spot price/performance and unless you want to game on 200fps or something, it can deliver enough frames per second for any use case.
Your build looks great, I would go for a cheaper motherboard and instead upgrade the 1060 to a 1070, but it works fine as it is too.