It is a game streaming platform. Any game you get on Google Stadia is in the cloud and can be played on any supported device. Right now it is restricted to wifi and hardwire but they will be opening it up to mobile data streaming later on.
Without having read all your technical details, i like the idea of a Demon class. Downvotes are probably from D2 purists. >_>
Have you ever played [Sacred 1]?(https://store.steampowered.com/app/12320/Sacred_Gold/?snr=1_7_7_151_150_1)
It was the first ARPG i ever played and i swear if they had more publicity it couldve gotten as big as Diablo. Absolutely still worth playing even to this day. Lots of content. The only thing that hasnt ages as well is the walking animation imo.
They also had a demon and a vampire class. Both i would absolutely love to play in D4.