1. Xbox sales were down 70%... So, why would developers limit themselves exactly?
2. How do you think Customers and devs would react to more platform lock-in? Devs WANT to sell more games
3. Developers would likely dump DirectX entirely, and just use cross platform libraries (they already are). Devs aren't going to limit themselves to Xbox only. And, toolkits like Unity abstract a lot of the lower level graphics from the developer. So, it doesn't even matter
4. If it will kill gaming in Linux, it would kill it more in windows, and Microsoft would piss off customers. I'm not sure how this would be a brag...
5. The biggest online marketplace is Steam... No sane dev is going to limit themselves at this point to only 1 platform
6. The DirectX features Madthumbs mentions DOES NOT MATTER. There are 50 different ways to solve the same problem, using non-vulkan libraries (or even Vulkan Extensions). DirectX is simply 1 solution.
7. "Antitrust".. Again.. And, I guarantee that the EU would be unimpressed...
8. Theoretical scenarios like this, are exactly why gamers should consider different platforms..

This nonsense is based on the idea that DirectX (which is Windows/Xbox only) is critical to game developers. It is not. There is NOTHING gaming requires from DirectX specifically, or Microsoft.

It also shows a complete lack of delusion about how users or developers ACTUALLY think.

"Yay", I can lock my game down more so less people can play it or buy it, all to help XBOX sales!!!!