This leads to some interesting questions. If a significant segment of Linux users abandon FOSS desktops such as KDE and GNOME for the Windows ecosystem, what will this mean for projects such as Firefox and LibreOffice? What will it mean for KDE, GNOME, and other FOSS desktop environments and window managers?
Now, there will be a contingent of Linux users who won't migrate to WSL for a few reasons. There are some Linux users who won't use Windows, whether it's due to certain features such as telemetry and ads or whether it's due to some other aspect of Windows they don't like. There are some Linux users who need to run Linux directly on their hardware and thus WSL wouldn't fit their needs. There are also Linux users who care about using a stack of software that is fully free and open source and thus wouldn't switch to SWL.
But will there be enough remaining users in order to justify further development of the FOSS Linux desktop in the eyes of major projects like LibreOffice and Firefox? We will see.
Linux Desktop users are there because it offers them a better experience for whatever they are doing. And WSL doesn't change it that much.
If you really need MS Office, you wouldn't be a Linux Desktop user anyways.
I honestly don't see WSL being a game changer for Linux Desktop. But I do see it improving the life of current windows users.
Microsoft just realized that those devs actually don't care about Linux as such, they just want POSIX like features, otherwise they would be helping OEMs that still try to sell Linux based systems.