It will never happen, but my dream is for the Asahi devs, Valve, and Apple to all get together to build out a cross-platform Proton to emulate and play games built for Windows on both x86 and ARM hardware running Linux.
A Steam Deck with the performance and power efficiency of an M-series ARM chip and the entire library of games that run on Proton is just...dreamy.
The end game for Valve isn't Steam Deck 2 or 3 (which is statistically impossible for Valve to produce), but for Steam to be on everything.
Most of the studios that own those games, and target POSIX like OSes on mobile phones and game consoles, are yet to bother with GNU/Linux versions for SteamOS.
What Valve want is the dissolution between platform/architecture and store. By my eye, it's the driving force of their efforts, more so than them selling hardware or being the open source good guys. Not to undervalue their work in helping make Linux a first class citizen for gaming, but the core of their business model is getting people to engage with their store, full stop, and being able to sell their games on Android (and elsewhere) would massively extend their reach.
This may go both ways too, there's also been indications that Valve have been tinkering with Waydroid, meaning Steam could also become a store for Android-native games.
- CD Projekt Red: released Witcher 2 on Linux, didn't for Witcher 3.
- iD Software: released Doom 3 on Linux, didn't for Doom (2016) or Doom Eternal.
- Epic Games: released Unreal Tournament 2004 on Linux, but didn't for Unreal Tournament 3 or Fortnite. (A Linux port was being worked on for UT3, but it ended up getting cancelled.)
- Larian Studios: released Linux version of Divinity: Original Sin, didn't for Divinity: Original Sin 2 or Baldur's Gate 3
Many studios over the years have made native Linux versions, and many studios stopped because the cost of porting exceeded the revenue it generated. Proton didn't exist when Unreal Tournament 3, Witcher 3, Doom (2016), or Divinity: Original Sin 2 released, so Proton wasn't the reason those studios stopped developing Linux titles -- they stopped because it made no financial sense to continue to make them.
Now, with Proton, 79% of the top 1000 games on Steam are gold or platinum rated on ProtonDB. If you're fine with minor issues, 88% are silver rated or better. For the Steam Deck in particular, there are 5,500 verified games, and 16,526 verified or playable games. So I'd argue Proton is doing quite a lot for people gaming on GNU/Linux machines, since they now have access to a solid majority of the top 1000 games on Steam, both on a Linux desktop and on a handheld.