What? The original WebAssembly announcement[1], which can be viewed as the manifesto for how WASM was envisioned, it clearly says "once browsers support the WebAssembly syntax natively, JS and wasm can diverge". Eich's goal with WebAssembly is not replacing JS, it's providing a better compilation target for other languages. WebAssembly is a replacement for asm.js, not JavaScript. No one is selling a lie here.
[1]: https://brendaneich.com/2015/06/from-asm-js-to-webassembly/
That certainly is a shame, but it's not like we have to accept that as the future. HTML is a document markup language, but we've hijacked it to build interactive UIs. It might be that WASM is just a native-ish FFI system for javascript today, but tomorrow it could be something completely different.
WASM can be great if they allow it to.