The news is that the Microsoft is offering Xiaomi to run Windows 10 free on the upcoming phone Xiaomi Mi4. Their partnership has not yet come top a conclusion.
MIUI is the current default OS based on Android for the Xiaomi phones. If this project goes well then Xiaomi might turn out like Nokia offering Windows phones for the consumers.
There are even some selected users in China and in other countries too who have access to these prototypes who will provide feedback to both Microsoft and Xiaomi which will decide the future of Xiaomi Phones.