Dynamic linking with a safe ABI, where if you change and recompile one library then the outcome has to obey some definition of safety, and ABI stability is about as good as C or Objective-C or Swift.
Until that happens, it'll be hard to adopt Rust in a lot of C/C++ strongholds where C's ABI and dynamic linking are the thing that enables the software to get huge.
Dynamic linking with a safe ABI, where if you change and recompile one library then the outcome has to obey some definition of safety, and ABI stability is about as good as C or Objective-C or Swift.
Until that happens, it'll be hard to adopt Rust in a lot of C/C++ strongholds where C's ABI and dynamic linking are the thing that enables the software to get huge.