Running a VM with a Linux distribution compiled for Arm does work, so why wouldn‘t we be able to virtualize Windows for Arm?
We would. For official support I think it depends on whether Microsoft sells/licenses Windows for ARM this way. In the meantime, there will be x86 emulated Windows machines pretty early in the Apple Silicon Mac life cycle. Probably will launch with them as there are already methods that work as was mentioned- QEMU, etc (hell, you can run it now on an iPhone, even if it isn't particularly fast).