It’s a pretty different amount of effort to Microsoft having to do a full 16 bit regression suite and make everything work and then support it for the fewer and fewer customers using it. And you can run a 32 bit windows in a VM pretty easily if you really want to.

I recently discovered that Windows 6.2 (more commonly known as Windows 8) added an export to Kernel32.dll called NtVdm64CreateProcessInternalW.

https://www.geoffchappell.com/studies/windows/win32/kernel32...

Not sure exactly what it does (other than obviously being some variation on process creation), but the existence of a function whose name starts with NtVdm64 suggests to me that maybe Microsoft actually did have some plan to offer a 64-bit NTVDM, but only abandoned it after they’d already implemented this function.