If you're a fan of cloud gaming, you may want to take a little look into Netris. The developers say it's a GeForce NOW alternative, one you can self-host with it being open source. They're also keen to highlight some Stadia-like elements of it too.
I hope this doesn't end up abusing family sharing (it's been just a few months since it became actually useful) to the point Valve nerfs it back to what it was.
TL;DR: Simultaneous library sharing. Before, only one user could use a library at a time. Now, up to 6 users can simultaneously play any game from the same library.
This is what Netris is touting users to exploit when they say:
Steam Library Sharing
Grant access to your Steam library, so everyone on your team can join in on the fun without additional purchases.
Oh, this is going to be fun! Google, AWS, or some other cloud provider will turn this into a hosted service, create a bunch of tickets for the opensource project and never contribute everything back, piss off Valve in the process, and somebody will get hurt.