What I also do not understand from that blog is how feasible it is to convert an Ethereum rig to a PlayKey rig.
Typical Ethereum rigs have multiple GPUs but barely any CPU power, a small amount of RAM and some of them run from USB sticks. If they run SSDs, they are usually the smallest ones , meaning there is little space left for double digit gigabyte game data, let alone games occupying 100 gigabyte or more.
Let's say you have 6 GPUs and you want to serve 6 gamers simultaneously. I think the rig will be bottlecapped by the things mentioned above.
That's a good point, and I think you've answered your question. I'm very sure that each miner is required to run full instances of the game (ie. they make it so that one miner does the GPU processing and a different miner does the CPU processing).