This is not "a prediction" - this is inevitably what's going to happen.
Everyone here who has drank the Valve kool-aid and pretends like they can do no wrong is dangerously short-sighted. Steam's virtual monopoly on PC gaming is a huge issue. You think Epic has a monopoly on the concept of "Store Exclusives?" Fucking spare me. It's a matter of time before Steam locks in its own exclusives, kills Proton, and locks every. single. game. behind always online DRM.
If you want to distribute your new PC game, guess what? You don't get to contract with both GOG and Steam. You don't get to say your game is Linux compatible because it runs well in the Proton compatibility layer. Oh, and if you say "games could run on Linux before Proton!" then you're deluding yourself by remembering a time when games were distributed with their own launcher and weren't packed to the gills with platform specific code so that the game integrates seamlessly with a specific third-party launcher and its DRM tools. You bought a Steamdeck? Cool. The version of Arch it runs is no longer supported. You have to upgrade to "Windows for Steameck." Yes, you have to pay for a fucking Windows license. Yes, it has fewer features than baseline Windows. No, it's not less expensive.
You think what's happening to YouTube is bad? Fucking strap in, boys. Welcome to digital content distribution in the age of unfettered capitalism. I wonder how many of you are gonna eat this shit up, huff lethal quantities of copium, and say it's "not that bad" once it starts happening and you're faced with either standing by your own stated convictions and giving up almost all PC gaming in general or bend the knee so you can get your precious Steam Library back. Probably most of you.