It seems to be a natural evolution of the technology. Probably it will take time for its adoption, but as the requirements for more complex apps and pages emerge, more people will move to it.
I read an article explaining the reduction in size of the code compared to pure java-script. Another benefit is its sharing mechanism with JavaScript - Apparently you will be able to use WebAssembly modules in your JavaScript code, so I see a great future for libraries and modules that require some performance to be written in WebAsm and JavaScript code will be its consumer.