Guile-Emacs was making a larger point about GNU: What if instead of each application being its own island, there was more of a shared infrastructure? A text editor (or any other GNU application) shouldn't have to concern itself with programming language implementation, they should be able to focus on their problem domain. GNU devs could use Guile as a solid base for user-extensible programs (something GNU as a whole is supposed to value, but in practice mostly doesn't except for Emacs and a few others.) I don't think this will ever happen because GNU lacks cohesive vision and leadership, but Guile-Emacs was a worthy experiment anyway. There is one success story in GNU, though: Guix. That project has demonstrated the mutually beneficial relationship that other GNU projects could have with Guile if they ever wanted to go that route.