RPi3 has 1 GiB of RAM. The system requirements of Windows 10 (cf. https://www.microsoft.com/en-us/windows/windows-10-specifica...) are 1 GiB for 32 bit and 2 GiB for 64 bit (both on x86). So I think if Microsoft is willing to, it should work, in particular if they slim down the fictional RPi3 version of Windows 10 (which I would strongly recommend).

I personally see the much larger performance regression for Windows 10 on RPi3 in the fact that at least on Windows 10 IoT Core there was no hardware acceleration of graphics on RPi3 when I last tested it (about a year ago), which caused it to feel rather sluggish.