I’m learning c++ via exercism because I’d like to use it for game development and other high performance use cases, and because it’s a good pip for the resume.

I think for game development you don't need to worry about a shortage of C++ opportunities any time soon. Both Unreal and Godot are built in C++ as well as many in-house engines. Similarly, there are other niches where C++ is king and it would decades for that to change.

That said, there are certainly areas where C++ is already being replaced by Rust. Areas where both performance and security are important are the first movers, such as webbrowsers, operating system components, but also things like high-frequency traders (crypto ones almost exclusively use Rust, while traditional ones will move slower).

Personally, I also used to be heavily invested in C++, but I'm happy to have moved to Rust myself. I recently became an independent contractor, and while I would be happy to take contracts involving C++ to migrate them to Rust, I would certainly not start new projects in C++ anymore. But for you, I wouldn't worry about that yet. The experience you gain working with C++ will help you appreciate Rust more down the line. Just keep in mind that at some point you will be likely to be exposed to Rust too.