I was wondering if JUCE will be supporting the Universal Windows Platform (aka UWP, aka WinRT) any time soon? This would allow us to run JUCE apps on devices like Xbox One, Hololens and Windows Phone which only run UWP apps. The Windows Store now supports Win32 apps in addition to UWP apps so that isn’t really a benefit anymore.
The majority of work seems to be in replacing the existing Win32 Windowing/Messaging code with WinRT code. While Direct2D support would be nice, it is not required at as you can just use the existing JUCE software renderer like you are already doing for Win32. Since WinRT uses the WASAPI API it shouldn’t take much to get Audio I/O working since that code is already in JUCE. The MIDI I/O code would have to be rewritten since you can only access MIDI devices using their new WinRT MIDI API: https://msdn.microsoft.com/library/windows/apps/windows.devices.midi.aspx
There is now a third way to access the WinRT API from ISO C++ called C++/WinRT that is probably much easier to use than WRL or Microsoft’s Non-Standard C++/CX. There was a talk about it at CppCon: Embracing Standard C++ for the Windows Runtime.