It's an interesting theory, but ultimately irrelevant. The thing is that there are SO MANY people working right now to make JavaScript incredibly fast. It's not hard to imagine a future where JavaScript is the fastest reasonable way to write software -- simply because it's the language that has the most R&D going for it.

Did I say future? Oh, hello NodeJS.

I don't envision that we'll be writing JavaScript itself forever -- but rather a super-syntax on top of it that compiles down to JS. CoffeeScript is the first generation of this kind of programming language.

I do, however, believe that for the foreseeable future, JavaScript will become the lingua franca of day-to-day programming.