The original steam deck was already exactly the product Microsoft should have made. There is now a whole class of similar (but generally more expensive) windows-powered devices. If Microsoft would have made the "XBOX Deck" they could have sold 10 times the numbers Steam Deck did.

But indeed, I'd think Phil Spencer's days are numbered now.

Well, hopefully, future XBoxes are fixed-spec PCs which run Steam AND some xbox frontend, and can switch between them as the user wishes.

There's no reason anymore for the xbox to be a different platform or hardware than PCs. An Xbox that is just a PC with fixed specs (or varying specs with some way to measure what spec you're compliant with) and which can use the Xbox store is probably all that people really want anyway.