Engineers and designers in Redmond never stop working to capture the next wave of digital consumers. Microsoft stumbled initially when it came to their mobile platform, but they eventually had a massive write off and moved to adopt iOS and Android as a platform to distribute their mobile apps.
However Microsoft is not done trying to capture the entire mobile pie. According to sources close to the company a new mobile platform is being developed to rival iOS and Android. This new mobile system will optimize for small screens, ARM chips, and long battery life. Consumers will have a simple and easy touch first UI which should be familiar to users of Windows 10.
However this new mobile operating system will not be compatible with any Microsoft technologies. App developers of Windows UWP or traditional Win32 apps will need to learn a new language and start all of their apps from scratch. Apps like Windows Mail and Calendar will look and work different. Also none of the UI will take advantage of the Fluent Design System.
I work as an engineer in Milwaukee. Currently I work on a few different UWP apps primarily Ink Calendar.