Technicaly Stadia is just a console on cloud running on Linux and Unreal engine, with the hardware configuration of a datacenter. The end user experience is still going to be dependent on the client side device and internet speed.

At present STS is hosting on AWS, so things arent much different + hosting gives more independance on scaling the configuration. I am sure Amazon is going to crush Google if this becomes a thing, afterall Twitch has more streamers than Youtube.

People dont trust Google with privacy. xD
(A duckduckgo user)