Linux dominates supercomputers for a long time: https://itsfoss.com/linux-runs-top-supercomputers/
Remember how Android is technically Linux ?
The risk here is for SteamOS to go the Android way...
but I have more faith in today's Valve than in Google of a ~decade ago.
At least for now, while Valve is still a private company and Gabe Newell is still leading it and still seems to be in good health and sound mind.
Sadly, this will probably only last for a couple of decades at best, but hopefully this is all the time that Linux (and libre software in general) needs.