There's no reason to suspect that browser implementors would sandbox wasm any less strictly than JS. Heck, there's no reason to suspect that they wouldn't just re-use the existing JS sandbox.
Thanks, kibwen. I'll make a stronger statement. By definition, wasm and JS are two syntaxes (initially co-expressive, wasm and asm.js) for one VM.
Do people actually read docs any longer? https://github.com/WebAssembly/ has some, my blog covered the 1VM requirement. There won't be a new "sandbox". JS and wasm interoperate over shared objects.
