> I think Emacs types would shy away from building JavaScript into their editor, having V8 be the engine, adding more layers of abstraction to understand and maintain, and splitting the extensions between Emacs Lisp and JavaScript. I'm also not convinced that a significant part of the community really wants this.

I'm reminded of when an old C hand tells me that Rust will never replace C because it's too complex, brittle, and frustrating for the kinds of applications C programmers use C for. I always tell them: Rust isn't aimed at you -- it's aimed at your replacement.

The Emacs-ng team doesn't have to convince the Emacs community -- they only have to convince their replacements. Much of computing in the very near future will be built on two languages: Rust and JavaScript. By basing Emacs-ng on those two languages, they just opened Emacs up to extension and hacking by a huge community who have no interest in touching Emacs's ancient, doddering Lisp nor its C underpinnings (C being, inherently, unsafe at any speed to work in). So ugly as it is, from a social standpoint it's absolutely the right approach and may well overtake GNU Emacs in terms of ecosystem size and vibrancy by the late 2020s.