I believe someone is working on an emacs in guile. That's the right approach. I don't believe it's necessary or sensible myself. I like Scheme a lot. But Emacs resembles CommonLISP more than Scheme so for Emacs future CommonLISP seems the most sensible option.
Anyway, we're ages away from any of that. Although I do believe we'll see a more capable LISP inside Emacs within a few years now.