> I don't think that JS & DOM scripting can be pushed that much further, like I'm having a hard time imagining that say 5-10 years down the line JS applications will be able to compete with native, somewhat computationally heavy applications (which is what I assumed was the direction in which this whole web thing was going).
You're still not getting it. Native (i.e. compiled from C/C++) computationally-heavy applications is exactly what asm.js allows!
The fact that it's a subset of JS is a clever hack that gets over the backwards-compatibility problems, but don't let that fool you -- asm.js really is a low-level compilation target.