I don't think 8k gaming will "ever" be a thing. Well... it will, just not widespread. 4k is about all you need unless you're going LARGE screen, or multi screen setups. I don't know how many people are going to be that seriously invested in gaming to want to go that far, and there's already people doing that.
At this rate, the only logial reason for 8k gaming is if you have a 60+ inch tv, or you want extreme sharpness in textures, but that's already pretty good in 4k. but who knows, maybe I'll eat my words.