You do know that there's no software available for it, right? Without software, arm64 Windows is not a viable operating system for an arm64 laptop. ARM Windows is as relevant as MIPS Windows or Itanium Windows without the huge ecosystem of software you get on x86.
And who goes bankrupt first to build this platform? Is it the laptops makers who lose millions investing in laptops that almost no one will buy because there's no software for them (actually, they already did that). Or is it the software devs who lose millions porting their software to laptops that no one owns? When Apple says the future is ARM, everyone knows the hardware will be coming and they'd better fire up their IDEs. There's no such confidence in ARM Windows.
Pretty critically, Apple was able to modify their chips so that they can efficiently emulate x86 code. Microsoft will not be able to do the same.
What I’m really curious about is how the ISA for the M1 is different from the CPUs Windows for ARM already supports. And as others have mentioned — I think GPU support will be more difficult, but I don’t have any data to support that.
But, it’s not like alternative (and mainstream) OSs don’t exist for ARM64. Maybe with some faster ARM64 CPUs, this could be the push to really make ARM a viable architecture for more than just Macs.