I mean, there's no strict need to have 'Xbox hardware' to do cloud gaming. You can do cloud gaming with PC systems. I think like every single 1st party release from them since 2016 has had a PC version, along with a bunch of titles before that as well. It would be a break of continuity for users, and it might mean losing older backwards compatible stuff, but it's all doable without any specific Xbox hardware. Heck, they could even just keep the existing Xbox cloud infrastructure, while also having PC hardware for any future generation games. There's no strict need for all the hardware for Xcloud to be homogenous.Microsoft will always need hardware. Even if Xbox's console install base is small, they are banking on growing the market via cloud, and those cloud servers are Xbox hardware, for better or worse. If they are going to offer a console experience via the cloud, then the cloud will be made up of the console.
Microsoft also has a history of success releasing it's software on rival platforms, from Office on Mac, Arrow Launcher on Android, Monster Truck Madness on GBA, and Age of Empires on DS, to the more recent examples like them publishing Ori on Switch. It's worked out for them in the past, why wouldn't they want to keep doing it?
And if Xbox's big gambit for the future really is cloud gaming, well....that doesn't really change the end conclusion too much here - that's still a recipe for disaster.
As for putting their games on other non-Microsoft platforms, it's not really something they have much history doing before recently, outside very select titles. The reason they shouldn't do this is because it clearly makes buying an Xbox, already in a losing position in the market, even less appealing. Exclusives have always been a seriously major factor in what console gamers choose to buy. If I can buy a console that both has its own unique exclusives and all the Xbox games, why on earth would I buy an Xbox? I'd just be limiting myself. I know we're not quite there yet, but it seems like that's the direction things are heading.
Thing is - it takes a huge amount of effort(and thus money) to put together and maintain a dedicated, new generation hardware platform. If they're not really getting any kind of healthy returns from it, and keep going with the 'we dont care how many we sell' mindset as sales keep cratering, then is it really financially responsible to keep spending all this money on that side of things? How does it make sense? It's been said plenty up til now, but Xbox is not going to succeed without some sort of clear direction. And consumers are absolutely picking up on this confusing, murky, directionless situation with Xbox right now. It does not inspire confidence. Not that I think giving up on dedicated console hardware is the answer personally, but it would at least give them some focus and help them run a lot leaner.