Did you see yesterday's article about the White House Office of the National Cyber Director (ONCD) advising developers to dump C, C++, and other languages with memory-safety issues?
The obvious comparison is Rust. There are way more C++ jobs out there than Rust jobs. And even if I'm hiring for a team developing something in Rust, I'd generally prefer candidates with similar C++ experience and a basic understanding of Rust over candidates with a strong knowledge of Rust and no domain experience. Modern C++ and Rust aren't _that_ dissimilar, and a lot of ideas and techniques carry over from C++ to Rust.
Even if the DoD recommends that contractors stop using C++ and tech / finance are moving away from it, I'd say we're still years away from the point where Rust catches up to C++ in terms of job opportunities. If your main goal is employment in a certain industry, you'll probably have an easier time getting your foot in the door with C++ than Rust. Both paths are viable but the Rust path would be much harder IMO.
Of course if you really need that non-memory safe stuff - which all your existing code does - then you can't take advantage of it. However you can migrate your C++ to modern C++ and add those features to your code. This is probably easier than migrating to something like Rust (Rust cannot work with C++ unless you stick with the C subset from what I can tell) since you can work in small chunks at a time in at least some situations.