Win32 is an OS API, which doesn't necessarily relate to the CPU or other chipset members. Do you mean it will Win10 for ARM will support code targetted at ia32/amd64 CPUs via emulation?

Windows 10 on ARM has been shipping for over a year, and it has an x86 (but not x86-64) emulator.

https://docs.microsoft.com/en-us/windows/arm/

There is a lot of Win32 using code out there.

It may even be the case that MS's long-lived flagship products (Office, VS) are not completely free of it.

In the event you are not joking, there are entire industries running on Win32. My industry alone (EDA) is a 100B dollar industry. I'm aware of many others.

VBA macros in Excel is my standard answer.

Everything that makes Windows worth using.

The installers for 64 bit applications.