> Asm.js is not a very sound approach, especially compared to technology like Native Client.

Yes, it is. NaCl is not portable. PNaCl is tied to the nonstandard and Chrome-specific Pepper APIs, to say nothing of all of the issues of LLVM bitcode.

> Rust seems promising, but won't be seriously usable until at least Rust 1.0, which still seems a long way off. As the year progresses, I get more and more doubtful that it'll be out during 2014, like was claimed earlier this year.

As someone closely involved with Rust development, I do not share those doubts.