Microsoft, like every tech company, applies for and receives many patents, not all of which are for products, services, and components which end up part of commercial products. However, the individual listed as the inventor for the latest Microsoft flexible hinge patent -- Kabir Siddiqui -- also has been a driving force for a number of other hinge-related Microsoft patents.
Microsoft officials said previously that Microsoft's focus in mobile, moving forward is on the business market. They've also said they consider Continuum -- the capability that enables phones to use large-screen displays and keyboards -- to be a differentiator for the company in the mobile space.
I'd bet if any kind of foldable Microsoft mobile device does come to market, it will be running Microsoft's recently announced Windows 10 on ARM operating system with built-in x86 emulation. If that's the case, I'd be surprised to see anything beyond a possible prototype Surface mobile device in calendar 2017, since that coming ARM operating system implementation is likely a Fall 2017 deliverable, at best.