Even if they go fully day one multiplatform publishing I don't expect them to get rid of hardware completely. It's what been speculated and talked about for months now. They may just end up shipping a less subsidized, or non-subsidized, enthusiast machine that is more PC-centric but runs some kind of emulation layer or shell or whatever to bring your digital library from Xbox forward.
They might be a software/services company, but they still have an entire consumer and developer ecosystem they want to keep you/devs invested in.
"Make the GDK the one-stop-shop for building games on Microsoft platform, including other PC ecosystems"
They want you using Visual Studio, and GitHub (and CoPilot), but also use middleware like PlayFab, Havok, Simplygon, etc, and cloud services like Azure. Then to tie it off they want you to sell your software on their Store. And that software will be "universal" and run on an Xbox or PC, so even if they are shipping to Steam it can still be easily packaged or sold on the Microsoft Store.
Why would they cut out the "Target Platform" part of this pipeline if it's still profitable and a key part of their vision?