SteamOS is still clinging on, somehow. Valve just released a new Beta that is mostly just security updates and Debian 8.9 updates.
Security updates are important of course, but each time I hear of a new SteamOS Beta coming out I'm always hopeful it includes something interesting. One of the only really interesting bits to this update is this line "steamos-base-files - udev rules from Feral to enable steering wheel support", good old Feral! Having good steering wheel support in SteamOS could be quite important in future, if we continue to get more top quality racing games like F1 2017, DiRT Rally and so on.
I do have a feeling that once Valve have managed to polish up VR support for Linux, that they might make a new splash for SteamOS and Steam Machines. I'm probably being too optimistic there, but I have to think that all their work on Mesa has to be for something. Right now though, it does very much seem like SteamOS itself is on life support, waiting for someone to come along and save it.
Thankfully with Valve working on Mesa, VR support and more, they're still doing rather a lot to help Linux gaming.
Thanks for the tip mphuZ!