The upshot: React developers -- who can build UIs for either the Web or for native mobile apps -- will soon be able to write native Windows 10 apps that can be packaged and distributed via the Universal Windows Platform.
Microsoft's support for React Native delivers apps via the Universal Windows Platform (UWP) packaging system, sending them to hardware in Microsoft's universe, including Xbox and HoloLens.
Thus, a React Native app is doubly convenient for the developer -- easy to program and easy to distribute. Facebook's F8 conference schedule app will be open-sourced as an example of how to use the framework.
That said, developers have been skeptical of UWP since apps developed with it run on only Windows 10 and up. However, Microsoft has reiterated its support for the format, offering tools for porting existing Win32 apps to UWP.