Do you have a source for that? All I can find on their Steamworks site is the rules on Steam keys being restricted, not other versions. Maybe I missed that email part in the news.
It only applies to Steam product keys though, so developers cannot sell cheap Steam keys on other platforms while still taking advantage of Steam's services.
Get a Steam Deck? You can hook it up like a PC, use it sat around. Though its not a powerhouse. Wait and see how the Steam Machine fairs? There's still a good second hand market for parts too.
Its a shitty time at the moment with scumbag companies and AI, so consumers are completely fucked.
Also: Fuck subscriptions.
Plus the game pass versions of games are complete dogshit compared to the Steam versions most of the time.