Microsoft’s Joe Belfiore, Windows VP (and former Windows Phone program manager) informed said that new features and hardware for Windows 10 Mobile “aren’t the focus” anymore. There will be fixes and security patches, of course, but you shouldn’t expect more than that.
As for why the platform has been all but dropped? The executive boils it down to one main reason: the difficulty of getting developers to write apps. Microsoft tried paying companies to produce apps. It even wrote them itself when creators couldn’t or wouldn’t get involved, but the number of users was “too low for most companies to invest.”
Whatever the reason, it’s safe to say that Microsoft isn’t just acknowledging that Android and iOS hold a clear lead. It’s quashing any hopes for a comeback, at least for the foreseeable future.