This is one of my concerns about MS potentially PC'ifying the Xbox. The added capability/flexibility this gives the device brings with it added complexity and more potential for hardware and software problems and I'm not sure that consumers looking to buy a console are going to want to make that trade-off.
While it's a valid concern, I don't think there's too much possibility of that for a variety of reasons.
If we look at it now, XBO is already on the Windows NT kernel. Not much changes between now and the Project Scorpio release except for possibly allowing more UWP applications to be run on console.
They're highly unlikely to implement a full desktop experience on the consoles for a whole host of reasons, not the least of which is that a low cost Xbox that can run all desktop applications undermines their OEM partners where it matters (volume PC as opposed to Premium PC like Surface). That isn't somewhere they are willing to go.
That means that many of the services that have to be run on PC just will not exist on an Xbox console (WOW won't be needed, for instance). That lowers the bar with regards to complexity quite significantly. The non-varying hardware also radically reduces the complexity compared to a standard version of Windows. Hence, it not going to be similar in complexity to something like say the Surface line (multiple hardware configurations, full Windows desktop support).
The console OS will be tasked with having to manage a far less complex environment than a full desktop OS. Drivers for the OS will be far simpler as well. USB on an Xbox will never have to potentially drive a USB display or USB audio, etc. You don't need anything there to support Bluetooth pens, Bluetooth audio, Bluetooth networking etc. The list goes on. In being a console, it requires a far less complex OS (and all the driver support that entails) than a full desktop. But that doesn't mean it won't still be the same underlying OS as that used on full desktop PCs.
Oh and one of the major contributors to OS instability? Video card drivers. On a console you can bet that for one, it won't be user installable and that Microsoft will strenuously test video stability as they do on the current XBO.
Regards,
SB