Given the rise of Nadella, I'm sure the new lockdown/home platform of Microsoft is going to be their cloud services.

Following the Google/Apple model of having cloud profiles maintain/inform/manage (depending on home/gaming/work platforms) all the Microsoft devices seems the best approach.

It's also what people want - they want unified logins (note: plural, Google!) so that they can get on with their work/personal/gaming needs and ensure that new devices that are platform compliant "just work" with minimal/no config.