[brudgers]

My understanding is that the 'Universal Windows Platform' is comprised of disparate multiple non-universal platforms such as desktops, mobile devices, servers, clouds, and IOT things. In practice this means that a UWP application targets one or more platforms and not all of them, e.g. Microsoft's UWP Camera app doesn't target the Azure or Server platforms.

My take is that Microsoft is in mobile for the long term and that its strategy has been to gradually migrate the target uses first addressed with Windows CE into the mainline of Windows and that Windows 10 is the realization of that strategy...we're back running Excel on mobile devices.

Windows Phone 7 was the first step in that direction. Windows Phone 8 and Windows RT were intermediate steps toward hardware agnosticism and away from Wintel strategies. I call it an intermediate step because apps for those platforms were [at least largely] forward compatible to Windows 10 and Windows 10 Mobile.