Honestly kind of surprised they didn't just build a subtle Windows 3.1 wrapper that would launch to run 16-bit apps, combining the view-of-the-system virtualization approach of WOW64 with ABI translation ala Rosetta.
Windows NT setup programs were traditionally 16-bit because every version of NT could run 16-bit x86. The non-x86 variants (alpha, mips, etc.) had built in emulation.
So Microsoft has already got the ability to run 16-bit Windows apps in emulation. It's a shame they didn't enable this on x86-64.
