Zig or C++, Which of these would be a good second language to know, while having Rust as your strongest / main language?

The more I look into C++ the more I hear about how its been replaced by Rust, or companies are at the very least testing the waters and trying to move parts of their code base away from C++ and towards Rust for safety and performance issues.

On the other hand, I've heard the opinion that C++ makes one more likely to get a job as a Rust developer, because you're the guy who can work with the modern tools of Rust and you understand legacy code bases.

However after working with Rust, Rust has kinda spoiled me. lol I now know that not all languages are built equal. Having modern tools really does make the developer experience better. This is why Zig catches my attention.

However I'm worried if Zig will be worth my time, because let's face it, Rust is just so damn good. Many have been asking why we need it when Rust is the better modern alternative.

Basically I see two potential futures:
A) Rust grows exponentially. C++ is still alive and kicking, and Zig never really grew any further.
B) Rust grows exponentially, and so does Zig to the point of being on the same level as C++. C++ becomes way less relevant as companies push towards more memory safe and modern languaages