Rewriting parts in Rust would require Rust to have good C++ interop, which it doesn't. At all. Rust has good C interop, so if your code is already divided into

Rewriting parts in Rust would require Rust to have good C++ interop, which it doesn't. At all. Rust has good C interop, so if your code is already divided into C-abi shared libraries then you're golden. But if it's not then Rust migration really isn't an option. And realistically I'm not entirely sure how you can add C++ interop to Rust without also ruining Rust. It's a hard problem to say the least.