This is great news. Microsoft is adopting/forking Rust. That means Rust will be supported for all eternity.
There are also Microsoft teams starting to use Rust, e.g.,
https://msrc-blog.microsoft.com/2019/11/07/using-rust-in-win...
Cool that MS is using something Ruat based. In no way does that opinion lead to a conclusion of ongoing support.
Windows on ARM is probably fine. Windows Phone and the like eventually lost (losing? I haven’t kept up) support, but phones are traditionally a 2ish year supported device and then they’re not targeted (specifically in the Android OEM arena). Windows proper they have business clients and if they don’t support it for a reasonable amount of time, Microsoft is basically hosed. It is, I imagine, why once they decided to kill off older IEs everything prior to latest and greatest was killed at the same time: they had supported them for far too long and it required killing them all Off in one move.
I’m pretty sure you’ve got your history backwards. GCC was created specifically to fill the need for a free C compiler for GNU. By that time C was already popular by association with Unix.
One reason of why I'm using Rust is because it's built by a group of people that I like, and Microsoft is not on that list.
However, I always keep a open-mind, I mean, I don't see anybody will be hurt if Microsoft become a direct contributor of Rust language itself. In fact, I could like Microsoft a bit if they did invest in Rust. I hope they do that <delete>instead of trying to fork things/build something alike (if that's the case here)</delete> (I watched their intro, their design is different than Rust and I somehow like what they did there).
If someone had told me ten years ago that my favourite code editing environment on the Linux desktop ten years later would be browser-tech-based, MIT-licensed, and made by Microsoft, I'd have stared at them like they had just grown a second head. But here we are. Interesting times, man.