It's simple. "Bytecode" is just a kind if encoding. The only thing it does is make programs marginally smaller and marginally quicker to decode. It's not enough to justify enormous switching costs. Let's talk about what functionality this new thing should have. That's where the high-value opportunities are. But, it's also where there's no easy consensus.

Hence, there are high value opportunities in JS as a compilation target/runtime platform.

You know what's a perfect, concise byte code? An ast-laden ASCII blob. What's the byte code for a byte array again? Oh there isn't one.... What's the byte code for a compare and swap? Shit....

Personally, I feel that the biggest slap in the face to developers in the last decade is that V8 uses native code instead of byte code. In 10-20 years I hope we look back on Google's decision to do that and hate them for it.

"In 10-20 years" - let's hope ES6 is released before that.

Honest question: why is it a slap in the face to developers?

Because we could then have a virtual machine that we could send bytecode to, instead of having all of these languages that compile to JavaScript, which eventually gets compiled to native code by V8.

it compiles to an ast first

Years ago at Camp Smalltalk, Smalltalk VM implementers talked about compiling everything to ASTs instead of bytecode.

I do understand why nobody would want to target Hydrogen directly, but here's a Hydrogen IR inspector tool: http://mrale.ph/irhydra/1/#ir

I think the point of contention is that there isn't really such a thing as a completely language-neutral bytecode, so nobody can agree on whose language-specific-js-replacement vm to ship.

If JS ever gets finalizers we could probably consider the total feature set JS has at that point sufficient for the implementation of most other dynamic languages without resorting to writing a VM in js or using asm.js to embed a full C runtime using arraymaps for a heap.

At that point we'd probably see some subset of JS devolve to a bytecode, I'll bet.

I don't think the dragon book will help unless the new edition has a section on how to organise a standards committee for your new language.