Looking at these OS market share charts I don't see for how much longer MSFT is willing to invest in the sector (hardware-wise at least) in a meaningful way:
Android and iOS now enjoy a global duopoly. Some numbers:
Apple and Samsung shipped a collective 551.2 million smartphones in 2015, trailed by Huawei, Lenovo-Motorola, and Xiaomi with 107.1 million, 73.9 million, and 72 million shipments respectively, according to recent Strategy Analytics data. Global smartphone shipments totaled a record 1.44 billion in 2015.
For the two other OS contenders, the numbers are grim:
Windows Phone and BlackBerry smartphones accounted for just 1.1 percent and 0.2 percent market share respectively during the three-month period ending December. The results are largely unsurprising, as Microsoft is scaling back its Windows Phone efforts and BlackBerry released its first Android smartphone last year.