Making Emacs popular again

A couple years ago I think Andy Wingo had gotten guile to the point where it could interpret emacs lisp. So the great mass of emacs functionality, including extensions, implemented in elisp, would run with guile swapped in as the implementation. There was no longer a need for a complete rewrite of all that elisp code. People who prefer to do so could write new packages in scheme and take advantage of guile's greater speed and capabilities. It came down to some remaining issues in the C code of emacs. I thought it sounded feasible, but I could be wrong. Can someone tell me what's untrue about that scenario?