WebAssembly will be more readable than asm.js, so it is an improvement over the current state of things,

https://github.com/WebAssembly/design/blob/master/FAQ.md#wil...

I do agree though that asm.js is less readable than handwritten JS. However, as others pointed out, when handwritten JS is minified, it also becomes quite unreadable.

Overall, I think WebAssembly will keep the web about as human-readable as it currently is.