Support for SteamOS v1/2, the one on Deck is rebased on Arch, lasted to 2018 which is when Proton entered the picture. If that wasn't good enough (fair enough) they were just PCs so you could install Windows on it if you felt you weren't being well served. Or a Linux distro, where the game experience is better than it ever has been largely thanks to projects sponsored by Valve.

So for the very few people who bought them, I'd imagine they're unlikely to be all that upset.