> While the hardware is no longer being sold the software sort of lives on. In an android app among other things.

It is built-in on every Steam. You can basically press two buttons and stream from your desktop to laptop if both have Steam with same accounts logged in.

> Tangentially it almost feels like steam could make a stadia like thing work. They have most of the moving parts including crucially, the bit google didn't, an established base of customers. Tomorrow steam could introduce a "play your games anywhere on any hardware" feature and no one would be surprised.

Already possible. While not so optimized as Games-on-whales.