An interesting idea, but...
Regardless of whether or not it's been done before, I think a highly extensible language with a flexible notation is an interesting idea and might have (as the author suggests) a lot of benefit in that the syntax and semantics of the language can be structured around the problem that one is trying to solve.
However in a production environment, it poses a number of problems. If this idea is carried through to completion, for instance it means that the guy who comes along after a chunk of program is written to do maintenance is going to have to basically learn a whole new language that supports these concepts instead of being able to rely on prior knowledge of how the language behaves.