So the Windows Subsystem for Linux GUI (WSLg) business plan looks like this, I assume:
Step 1: get lots of devs using WSL / WSL GUI.
Step 2: Get them comfortable with flexibly using WSL GUI on Linux and Windows interchangeably
Step 3: roll out your poison pill: new Version X, offering great compatibility on Windows but bad integration with Linux; maybe Linux support is buggy or nonexistent, maybe the API doesn't mesh with Linux systems at all, maybe it has license conflicts and Linux has to do a rewrite to be FOSS or write a hacky FOSS shim. Whatever creates the most pain for Linux / FOSS users.
Step 4: Stuck with being tied to WSLg, Developers go to the business and say "either we have to spend a lot of time fixing Linux issues or we buy Windows licenses" at which point the business happily buys Windows and Office 365 volume licenses and keeps going.
Step 5: Microsoft maintains its monopoly for another 10 years.
The "I want to stay independent" workaround is (I assume) writing API layers that can serve "thin GUI clients" on multiple platforms (I guess like Electron or a regular web application or something.)
> Whatever creates the most pain for Linux / FOSS users.
Not necessarily to this level of malice.
Many (most?) Linux users, especially new ones, use also Windows, so all it needs for MS to convince them to use only Windows+WSL and not say a dual boot machine or two machines, is something that just integrates the two systems, so that most users will feel more comfortable running everything under Windows.
The killer product in my opinion would be something that allows accessing to Windows internals and GUI from a Linux program (imagine "/usr/bin/excel", a port of Excel that works only under Windows+WSL). Those functionalities would be offered by something that "pure" Linux distributions could not offer, including WINE, since we're talking about the full OS and not an API translation layer.
Once users and developers are accustomed to it (many devs already develop under WSL) we'll reach the point in which the two worlds will fork in favor of Windows: what is developed under Linux will also work under Windows+WSL but not the other way around. That would probably be the moment MS will introduce their own Linux distribution (advertised as the only one that can take full advantage of "most recent Linux developments") that under the hood could either be normal Windows+WSL, or a different one containing a "hidden" Windows blob allowing developers to run native Linux, hybrid Linux+Windows, and possibly native Windows apps, either free or a lot cheaper than Windows+WSL.
If this happens, most Linux users, especially desktop ones, would rather go back to Windows rather than for example stay with Ubuntu+WINE. Server, embedded and other smaller niches users will make an exception, but Linux is in serious risk of losing all other users.
The things that make me not like Windows are it's aggressive Windows Updates, lack of real true security, and the way windows regularly ignores settings. Steam automates configuring Wine for you and most games just work. But for work? There's no reason to use Windows anymore unless you have some proprietary software that runs only on Windows.
Btw the whole "Access Windows internals and GUI" from Linux already works. You can just run Windows commands from bash and of course make scripts using those commands so essentially all windows command prompt commands are available to you now.
But remember it's Windows. You can set all the registry settings you want but it will still sometimes ignore your settings and just do what it wants.
Step 1: get lots of devs using WSL / WSL GUI.
Step 2: Get them comfortable with flexibly using WSL GUI on Linux and Windows interchangeably
Step 3: roll out your poison pill: new Version X, offering great compatibility on Windows but bad integration with Linux; maybe Linux support is buggy or nonexistent, maybe the API doesn't mesh with Linux systems at all, maybe it has license conflicts and Linux has to do a rewrite to be FOSS or write a hacky FOSS shim. Whatever creates the most pain for Linux / FOSS users.
Step 4: Stuck with being tied to WSLg, Developers go to the business and say "either we have to spend a lot of time fixing Linux issues or we buy Windows licenses" at which point the business happily buys Windows and Office 365 volume licenses and keeps going.
Step 5: Microsoft maintains its monopoly for another 10 years.
The "I want to stay independent" workaround is (I assume) writing API layers that can serve "thin GUI clients" on multiple platforms (I guess like Electron or a regular web application or something.)