At BUILD 2017 Microsoft showed off Windows 10 ARM, and confirmed for the first time that your existing x86 Windows apps will also run, even when downloaded directly from the internet.
This is due to the x86 on ARM emulation layer, and in the video, they show downloading and installing the x86 version of the 7zip app directly from the internet.
They note no user or developer intervention is needed to make this work.
The emulator relies on the Windows on Windows layer, which is already needed to run 32bit apps on 64bit processors. UWP apps from the store need no translation and already support ARM.