We had the discussion of the name here on Hacker News when WSfL first came out. I and others pointed out that these subsystems are, and have been for decades, effectively named after the kernel that is actually left out and replaced by the Windows NT kernel. There wasn't an OS/2 kernel in the OS/2 subsystem, for example.
That was originally known as Xenix V and was released in 1985. IBM sold it as Xenix 2.0 at the time. SCO was using Arabic version numbers by 1988, when it was up to Xenix 386 Release 2.3.
edit: I'm having a hard time coming up with a name which would be correct and Microsofty enough. But I think it would be a oxymoron.