I don't think Linux will be affected as much. Moreover, Linux is better than ever:
- you can buy laptop with Linux from two companies: Dell and System76, soon from Lenovo
- performance can't be beat (especially for development, with native docker and kvm for virtualization)
- amazing package managers, with fwupd you can even update firmware
- graphics stack is really good and getting better, firefox on wayland with video decoding support, wayland with great hidpi support
- work on chromium on wayland in progress (beta already available), we will have electron apps with hidpi support
- no bloatware (candy crush, 100s of processes...)
- gaming with Proton is miles better than gaming on macOS, still behind Windows for known reasons
Obviously if you need Adobe/Office, Linux loses many points :)
Oh, and WSL1 was banned, of course, on the grounds of being "too expensive and uncertain to support". You could have a Linux VM though, with approved distro, same as what prod machines run.
So really WSL is still confined to a small domain of switchers tired of MBP keyboards, Linux is safe for now :)
Seems like with WSL2, one could run Windows but do all the work using native Linux tools while enjoying quality integration with Windows. It's not a setup I would actually prefer over Linux but it should make any work where Windows is required much more pleasant.
On a personal level it's interesting that Windows is getting WSL right around the time when I stoppped booting my Windows install for games. Proton has been amazing, changed Linux gaming completely almost overnight. It's still not the same experience as on Windows, but between Proton and even the occasional native Linux port of a big-budget game - no longer an extreme rarity - I've been able to play games on Linux like never before.
In my opinion, WSL2 is leveling out the playing field between Windows and MacOS. If you were doing web development (and many people are) it had always been so much easier to get up and running on a Mac. MacOS had native versions of all the stuff web developers use (Python, Ruby, PHP, etc.), on Windows things were always surrounded with a haze of "unsupported" and "non-standard". WSL2 doesn't entirely resolve this issue but it goes a long way towards getting it done.
For myself, I have to do a lot more native Windows development and have had to switch from using Linux at work to Windows (running Visual Studio in a VM under Linux all day just wasn't cutting it). Having all the familiar tools available in WSL2 has made the transition much, much easier.
It seems like a very smart move from Microsoft. They get rid of the abysmal performance of windows's file system and spawning new processes by using... linux! Provide also an excellent terminal so that developers have the best experience with command line tools, all this without leaving the convenience of Windows!
Not surprising since they dominate the desktop market since forever being smart at strategy.
The only weak point of WSL 2 to my point of view is that you say goodbye to development of native Windows application because you are effectively on Linux. It means you either setup cross-compilation which can be annoying either you go with Visual Studio, the old MS way.
For the moment I will stay with MSYS2 plus Mingw64, they are both excellent and provide a good experience to develop native applications on Windows. At home I will keep using Ubuntu, of course.
For the introduction of WSL 2, I think many of the people using Mac OS X may switch to Windows. They never fully embraced the free-software philosophy and chose Mac OS X because of the high-quality hardware and software and the good terminal experience with unix-like environment. They will easily switch to Windows now.
The small group of people using Linux will probably stay on Linux because of dislike for Microsoft practices and the fondness for free software.
Bad news for free software, good news for Microsoft shareholders!