Everyone here is missing the elephant in the room: Make a PSN game that mines for bitcoin or an Xbox Arcade game that mines for BTC. It will be miniscule, like a 1.25 7990 which is 6GB ddr5. I would suppose that puts a PS4 within the ballpark of 1.25 MH or 1250 KH.
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Overestimated.
I would expect between 0.2 to 0.25 MH/s. That doesn't makes elephant smaller. Make addictive freeware game and solo hashrate doesn't matter at all...