Here's the chasm I want to see Rust cross: 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.
The C ABI can already be used, it comes with all the existing safety guarantees that C will provide. Isn’t this as good as C?
It's also as bad as C.
I'm saying that the chasm to cross is a safe ABI.