Not post-Ballmer. Azure is where growth is and Linux is a huge part of this. Microsoft's future revenue is directly tied to the success of Linux in the cloud so these old idioms from the 1990s died along time ago.
Is there any evidence that this is actually what's happening? Why does everyone hold on to a 20 year old mantra from a nearly totally different company? Especially when the "extinguish" phase is quite literally impossible. I get spite, I get hating MS, I get it, I really do. But this is pretty clearly not what's happening here.
If anything, this is a stab at Apple as it's reaching for web developers using Macbooks. Nobody who uses Linux because they want to is going to use WSL.
We repeat the mantra because it's Microsoft's own flavor of the same tactic that many have used before, and will use in the future too. The strategy itself is not unique to Microsoft, it's just a way to gain power over an established player, and I don't expect Microsoft, or any other entity in any power struggle, to play any nicer than the laws allow them.
That doesn't answer my question though. Is there any evidence that this is what is happening here? If there is, is the "extinguish" phase even possible? I think the answer to both is "no".
I don't think we'll have evindence, before the fact. But I think that they can gain a lot of control over the Linux ecosystem with WSL. If they introduce new features which people like, and don't make them open source, then the open source ecosystem is either forced to play catch-up, or face becoming less attractive. And now we're talking developers, not even regular users. Imagine 5-10 years passing, a slew of newer generation developers entering the job market, all of them raised on Windows, MS Office, GitHub, Visual Studio and WSL. They don't ever need to leave the MS ecosystem to do their work, and I wouldn't be surprised if they would think that a Linux desktop distribution is like a lamer version of something that works so well as part of Windows. And if this happens, that I'd consider the Extinguish phase.
Buy why is that beneficial to MS? Desktop Linux has no "market". The servers your deploying this code to is still running Linux. You can still have your Red Hat Enterprise Support contract or whatever you'd consider the Linux "market" to be while you're using WSL. What exactly are they trying to kill?