Microsoft got rid of Windowsphone to ride the next wave. To jump ahead of the competition. One such wave was AR with Hololens and Windows Mixed Reality.
However the competition, Apple and Google, are entering the wave without any real new hardware. Instead they are leveraging the device people already have – the mobile phone.
Both companies seem to think consumers will use AR via the mobile phone acting as the lens and the interface. Hololens could remain stubbornly tied to the enterprise and maybe gamers. That need not be a bad thing for profit. However it could be that Microsoft ends up being locked out of consumer applications for AR by not having a viable mobile platform.
Moreover if the world is going mobile as the primary personal computing device the pre-requisite for the “next big thing” could be a viable mobile platform.
Microsoft may not care if consumer devices for mobile are not made by them if they run enterprise cloud services. I am not sure if Microsoft can find the next big thing for consumers now they are out of mobile.