There were strongly persuasive arguments against C++ when this was first litigated, and while those arguments have been blunted by C++'s progress in the ensuing time, at this point, if you're going to introduce a higher-level language to the kernel, it might as well be something with pro-forma memory safety, like Rust.
I am waiting to see the reasoning why creative uses of Rust macros or generics aren't problem in the Linux kernel versus Ada/C++ (yes there was an Ada based distribution on the early 2000's).
There are plenty of OSes using C++, at very least on kernel drivers.
I'd say it would be worth it for drivers, especially if someone comes up with a stable API so that there can be a competing Rust kernel that reuses the drivers.
