Point taken, and you're right that in a certain sense Rust is proprietary, with all of the very real downsides that that entails (for example, the risk of tight coupling of programs to rustc, as hard as we try to prevent it). But I still think it's a fairly irrelevant thing to bring up, because Rust isn't targeting a large, open, multi-vendor ecosystem (as I specified in my original post). If Rust catches on, no other vendor is going to be forced to implement anything; nobody outside the current Rust community is even asking for a seat at the design table. The only real downstream dependency that the success of Rust might impact is LLVM, and we actually have maintained a pretty good relationship with the LLVM community from the start.