Stuff like GEForce Now is already great for that "core" gamer market that wants to be able to use their existing steam library but play them on their phone on the go or whatever, but that's a pretty small market because most "core" gamers would never use a streaming service as their primary system so the market is fairly small (latency, resolution, quality etc is poor compared to native).
But nobody has properly targeted that more general "I want to play games with zero up front effort or knowledge" case yet. And I suspect that's a pretty big market.