Back in June Brendan Eich announced WebAssembly:
WebAssembly, “wasm” for short, .wasm filename suffix, a new binary syntax for low-level safe code, initially co-expressive with asm.js, but in the long run able to diverge from JS’s semantics, in order to best serve as common object-level format for multiple source-level programming languages.
More from Luke Wagner and Eric Elliott. Details are being hashed out in the design documents.
The big question in my mind is performance. Porting over various native libraries to WebAssembly ( assuming a future where this all more or less works ) will only be compelling if they can run at speeds comparable to native apps. It will also need to balance that with battery life.
If you were looking for a moonshot project, this will be a fun one to watch.