The code is there in Visual C++, and people could already built native ARM applications to run on (jailbreaked) Windows RT. But reading between the lines, it seems that MS will not currently offer that option, but rather encourage people to write UWP/Modern apps, and emulate x86. MS themselves are compiling Office natively for ARM (like they did for Windows RT, and like they do notepad, calc, ...).

I wonder how UWP apps work technically on ARM. I heard apps will be compiled on the fly to run on ARM. Managed code (C#) just runs on the CLI or can be AOT compiled. But C++ is also a first-class citizen. Will you ship x86 code that is emulated/recompiled, or will you ship both x86 and ARM, or some kind of intermediate representation (like I think you do on iOS)?