> I wish that the project, talked about for years, to rewrite Emacs and base it on Guile would take off. It would save Guile
Exactly, and this is exactly its problem. It is not the Emacs people who are pushing this rewrite, but the guile people. in order to get a "killer app" as a vehicle to advertize Guile, because nobody else wants to write a killer app in guile from scratch.
Of course, Emacs would benefit from an vastly improved Elisp engine too, but my feeling is that the usual Emacs users actually do not want to switch from Elisp to Scheme in the long term. Elisp is a descendant of Maclisp, and as such much more resembles the look and feel of Common Lisp than Scheme. There is even a big subset of Common Lisp implemented in Elisp. There is no similar Scheme package, because Emacs people do not like Scheme. They like Lisp.
The problem is, even though they have two Lisp implementations under their umbrella, CLISP and GCL, GNU made the decision to _not_ use Common Lisp as their "official" high-level language some 20 years ago, because RMS had problems with Lisp companies during the 80s, and they are now sticking with Guile no matter what against all opposition. It was a bad decision, but now they have invested 20 years of effort into guile an do not or can not go back. The push to get Emacs onto guile is purely political. I have the feeling that the political push by GNU to start writing in Scheme instead of Lisp will alienate a lot of people in the emacs community and maybe lead to a fork.
In short: Pushing people to write Scheme instead of Elisp will either lead to Emacs dying (because people do not like Scheme) or lead to a fork (because people do not like Scheme). If you absolutely have to rewrite Emacs because the Elisp engine is so kaputt, rewrite it in Common Lisp. Having a high quality Common Lisp available with every Emacs install would benefit _Emacs_. Having Guile installed with every Emacs will only benefit Guile, but Emacs will die. And why? You'll guess it, because people simply do not like scheme.