If anything they will build a competitor to Steam Deck and Switch.
What would they get out of it?
I don't know, get out of retail hardware and potentially increase market share by allowing manufacturers to tailor devices to their respective markets? I'd just like to see more variety tbh (look at the plethora of handheld PCs), brought with a heavy dose of nostalgia for the home computer days.
See my reply to the other post.
The "OS and infrastructure", alongside whatever certification program to call it a "XSX", would require the use of Microsoft's XBOX game store. Microsoft would make a cut on any sales plus their own first party titles.
So basically the Steam Machines or the 3DO concepts. We know they don't work for the manufacturers because they can't be priced competitively against regular consoles that can subsidize hardware with game sales.
Maybe it could work if you're a registered XSX manufacturer, you get a cut of game sales. Since it'd probably be a digital only system, it's possible to administer in a way that the 3DO couldn't. AFAIK, Valve didn't do this for Steam Machines.