> just generate, in a loop, a series of assemblies that each purport compatibility with Windows ABI vX.Y.Z

The Microsoft developers already thought of that trick. What you declare is not compatibility with "Windows ABI vX.Y.Z"; you declare compatibility with an UUID which represents that Windows version. That is, if you're compatible with Windows 8 you say "I'm compatible with 4a2f28e3-53b9-4441-ba9c-d69d4a4a6e38", if you're compatible with Windows 8.1 you say "I'm compatible with 1f676c76-80e1-4239-95bb-83d0f6d0da78", and so on. Since you cannot predict the UUID for future Windows versions, you cannot pretend to be compatible with them.