Earlier quoted context omitted.
It seems just the opposite to me. The Windows Subsystem for Linux seems a testament to the NT Kernel and its deliberate approach from nearly three decades ago. Designed originally to support Win32, POSIX, and OS/2 frontends, for a long time it only ever really needed to exercise one of those things. Now it has the best POSIX layer it has ever had, focusing on byte-for-byte compatibility with binaries targeting the Li…
I don't think we'll ever see Win32 retired. .NET and UWP aren't distinct subsystems; they run atop Win32.
UWP is closer to being a distinct subsystem than "running atop Win32". Though it isn't an official subsystem, it has some of the hallmarks of one (and that was one of the complaints about Windows 8). They've been successfully blurring the lines between UWP and Win32 since Windows 8, but it's also not entirely accurate to state that UWP "runs atop Win32". (The old .NET Framework does, yes, but I didn't mention the .NET Framework, I mentioned UWP.)
If anything, with increasingly more of the Windows Shell moving to UWP, it may even start to be increasingly the case that it is Win32 running atop UWP.