The whole "is Rust relevant" feels like that needs the Ousterhout "A little bit of slope makes up for a lot of y-intercept" graph[1] stapled to the same.
I'm not sure what the y-intercept of Rust is, but its slope seems to be pointed towards more code being written in it than ever before. For example, the wasm compilation is probably the clincher for my toy projects because I like to build stuff to run on a website, but I don't always like writing in JS.
You just have to look to domains where C++ rules to see that while the community is aware of Rust, hardly anything is happening in HPC, HFT, GPGPU, Khronos APIs, LLVM/GCC, MPI, OpenMP, AUTOSAR[0], Unreal/Unity/Godot, PlayStation, XBox, Switch, Apple and Windows official APIs,....
So while Rust is being adopted, it is at the same scale that C++ was against C around the early 1990's, in regards to market size adoption.
[0] - They are looking into it, still no standard update that allows for Rust
An official work in progress Windows binding, still far behind of what C# existing bindings are capable of, or legacy toolkits like MFC.
Also given how the team has managed C++/CX transition to C++/WinRT with lesser tooling stuck on C++17, dropped Modern C++ bindings [0][1], before going into other shinny thing, I wonder how long they will keep at it.
It doesn't matter if the project is driven by Microsoft or not, the cat (of automatically generated language bindings) is out of the bag. E.g. Zig is using the same approach without being an official MS project: https://github.com/marlersoft/zigwin32, and Apple has an automatically generated C++ API for Metal (https://developer.apple.com/metal/cpp/).
In the future, the question won't be "what language do I need to learn to code on this platform", but instead "where are the language bindings for my favourite language".
I think it's just a balancing of where work is needed.
C++/Cx (and it's predecessors) was bad in requiring special compiler support whilst WinRT had already seen real adoption and cppwin32 didn't really give any benefits apart from another backend so they seem to have concluded that C++ devs would easier be supported by something more mature (that needed support anyhow) and then just focus the win32metadata project (That's still alive) on "new" languages.
Adoption by WinDev, nobody else cares after they screwed their customers.
They should all have been fired if it was up to me, we don't pay VS licenses for killing our workflows like that.
WinRT is Windows only technology, who cares about extensions.
Plenty of people don't have any issues with GCC and clang extensions, or macOS specific ones like Objective-C++, or TI, or ARM SDK, or whatever fancies their party, only MS ones are bad.
Rust is being used where it makes sense--generally security. So, gamedev won't use it for main loops but will use it for networking code. The crypto Ponzi brigade chose Rust for a reason. Some of us who write communication stacks (TCP/IP, CANBUS, etc.) try to use Rust whenever possible.
However, you are correct in that Rust popularity is growing, but it's going to be slow. If you look at the TIOBE index, there is a limit as to what Rust can really displace. A lot of the top languages are now GC-based, you're not going to reach for Rust if you can use those. So, Rust can realistically only displace C, C++, and ... nothing else. That means almost 75% of programming language use cases aren't even in scope. And C programmers really aren't going to gravitate to Rust as it's more of a C++ replacement.
So, you need a specific usecase (security) or a greenfield project that would use C++. That's going to be a slow climb.
I'm not sure what the y-intercept of Rust is, but its slope seems to be pointed towards more code being written in it than ever before. For example, the wasm compilation is probably the clincher for my toy projects because I like to build stuff to run on a website, but I don't always like writing in JS.
[1] - https://gist.github.com/gtallen1187/e83ed02eac6cc8d7e185