I can see it now. Most ROMs would be available, but Nintendo would be notably absent from any of the platforms and only allow their ROMs to be streamed from their own service.
Oh, I know, but in the theoretical world where there's a Netflix like subscription, I would assume that means a lot of different IP was also gathered there, like Sega, Atari, older Playstation and Xbox titles, etc.
There's not a lot of incentive for some of those groups to come together, but I imagine even if most could be assembled, Nintendo would be particularly resistant.