I'm going to say that it probably is... the question is whether anyone is motivated enough to do it. Microsoft's culture of back-compat is not only for third-party applications, so it shouldn't be surprising that e.g. various apps from an older version of Windows would run on a newer one. I use the XP calc.exe on Win10, for example.
The somewhat-underground far-East communities have made weird chimeras of different Windows versions. I've seen Windows XP explorer.exe running on a Windows 7 kernel. No idea how stable or usable that is, but it's been done before.