Having followed the whole #GuileEmacs debate a few years ago, I was (and still am) surprised that #Edwin, the Emacs-family editor integrated into #MITScheme, never came up in these discussions.

While it certainly lacks the bazillion libraries that power #Emacs, Edwin is as GNU Emacs-like as it gets - and it's programmable in #Scheme! It has a great buffer/listener combo, an #Info reader, shell facilities, you name it. Any Emacs user would feel right at home in it. And also: Scheme, man, Scheme!

So, obviously, a Scheme-powered Emacs is not only possible, it has actually existed for quite a while now.