Are you saying that Microsoft might make some change to their API that would be difficult or impossible for Proton to replicate? Otherwise I don't see the issue with targeting Windows and letting Proton handle the compatibility.

I am saying Proton represents Valve's failure to make SteamOS attractive to game developers, many of which are already targeting existing Linux APIs via Android NDK.

Also note that PlayStation makes use of FreeBSD, yet another UNIX based system, even though they use their own proprietary 3D API.

What Microsoft might do, there are legal and technical options they can take, remains to be seen what.

> I am saying Proton represents Valve's failure to make SteamOS attractive to game developers

Sure, but I also think it was a matter of getting a huge library of games available on the Steam Deck immediately. Instead of waiting for every GameCo to port their game over to SteamOS, which may or may not happen no matter what (the console world is full of entropy from what I can tell), they can get like 90% of every single game on Steam available on the Steam Deck right away. I don't know exact numbers, but the Steam Deck might have the largest technically-compatible library of games out of any portable console at this point, although a lot probably aren't well optimized for it.

But of course, this leads to Proton also being a crutch; if you know that Proton is going to do a decent enough job running your game on Linux, there becomes little incentive to spend extra time and money getting a native Linux port on there.

It's tough to say. IANAL, but I feel like if Microsoft were going to do anything about the API emulation scene, they probably would have done something about Wine in the last thirty years. I think they're way more likely to do something funky with DirectX that is difficult or impossible to properly translate into a Vulkan shader, thus breaking compatibility with newer games.