That would be WSL wouldn't it? Their goal is clearly to avoid having people moving to Linux as a development platform, and keep them on Windows.
The extensions are the ability for Linux processes to integrate with Windows software running on the same machine. In a way, they're extending Linux with Windows services.
I think it's the opposite. There's little danger that Windows shops are going to move to Linux. However, I know a bunch of devs currently using Macs that would probably switch to Windows with nice devices like the Surface Pro and access to real gaming and such, if only Windows was a suitable Unix environment for their work.
They want devs using Macs and such to move to Windows, and I think it's going to work.
For WSL 2, they're taking the Linux kernel whosesale and dropping it into a VM in Hyper-V. If anything, they're backing away from anything that could be construed as a possible EEE.
I like when a company wins by just being superior (and hopefully in a way where they aren't deliberately building a moat)
What good? All that open source code.
The constant goalpost moving here is ridiculous. “Oh, Microsoft released n projects as Free Software? Well by god they should have released n+1.”
Either way, because C#/.NET and Roslyn are open-source, the likelihood of .NET shops being left high-and-dry without a debugger is very slim, since it wouldn’t be all that hard for an experienced developer to build another one.
We're all right to be cautious about trusting large companies' motives when they embrace an open standard. But I don't think there's any reason to invoke EEE! until they have introduced a proprietary (i.e. closed-source) implementation of something and then added non-standard extensions.
Since much of Microsoft's recent activity has been released as open source (MIT licensed, no less), I have a hard time believing Microsoft would go down that road again any time soon.
Rather, I think they're building their business on providing the best and easiest-to-use hosting and cloud services provided you're using their excellent and free developer tooling. And I'm OK with that, since they're not doing anything that is unfairly competitive. (Even AWS could start providing VSCode extensions and they'd be on equal footing with Microsoft, though to win they'd have to compete with MS's cloud directly.)