If mining doesn't let up, I think PC gaming will simply revolve around integrated graphics, e-sports titles and other easy to run games. "High-end" gaming will be strictly console with more emphasis on and support for mouse and keyboard to take up the slack from people who previously gamed on PC. Simply put, PC gaming will not be replaced by console, but it will migrate to console. Consoles are a relative safe haven from mining and can benefit from an increase in supply since miners aren't buying them all up.
If mining doesn't crash, then PC gaming as we know it is simply done. There's just no way around it. Even if they build new fabs and increase supply by 10X, I am certain that miners will simply buy up all the GPUs instantly. They have no limit and will simply buy all of them because profits scale with numbers of GPUs. Consoles will benefit from that increased supply though and gamers will be able to buy them. This might not be a terrible thing.
Consoles are more powerful and capable than ever and TV's are excellent at high refresh gaming these days. I can see PC gaming migrating to a console environment where that one ecosystem will simply cater to both console gamers and former PC gamers.
This would be fine with GPU makers as well. They will always sell as many cards as they can possibly make and at much higher prices than gamers were ever willing to pay. With VR taking off with it's standalone headsets and consoles and TV's being better than ever, I am oddly optimistic even if PC gaming dies. That high-end gaming demand will not go unserved.
EDIT: I must say more. With PC gamers migrating to console, I can easily see Nvidia and AMD still catering to high-end gamers by making special "enthusiast" grade consoles, like the PS4 pro version but better. If the demand is there, they will make them. Consoles may be nearly indistinguishable from a high-end gaming PC, but focused on gaming of course. It would benefit from a stable and consistent development platform, allowing for better optimization and ease of development. The driver nightmare would be over for developers, or at least greatly eased. The death of PC gaming may be exactly what gaming needs. With death comes new life. You need both, and to be quite honest, I think we're due for a big shakeup in the gaming world. This could be the catalyst that makes things interesting again. Gaming could actually be exciting again.
I hope ETH shoots to the moon so hard it blows a hole through it. The most exciting time to watch and see what happens is when you have no idea what's going to happen. I say bring it.