Microsoft was about to start testing x64 emulation on ARM devices running Windows 10. However, this had no chance to happen until December. Microsoft has finally announced that the feature is now available with Insider Preview Build 21277.
It looks like Microsoft is working on 64-bit (x64) app emulation for Windows 10 on ARM PCs. The feature might be introduced in 2021, removing limitations on software use on ARM PCs.
During WinHEC 2016 (Windows Hardware Engineering Conference), Microsoft made the announcement that they are working together with Qualcomm to bring Windows 10 to Snapdragon ARM mobile processors. It looks like Microsoft has already started uploading ARM64 builds of Windows 10 to Windows Update.