As an Emacs user for ~10 years the greatest deterrent is it being single-threaded and lisp. I just can't understand the love for it. I've spent countless hours customizing my own configuration and I just can't enjoy lisp. Emacs's source code is also hard to understand and contribute to (let's not talk about lisp.h).
I'd rather have a new editor (or emacs fully re-written) with the same mindset as emacs - near-full customization via a modern scripting language (lua?) and/or c/cpp plugins, and text-centric. I don't care for fancy UI or buttons it could even have the same look and feel which I love
There is a some effort in Nim, called moe[1]. Nim has a lot of features similar to a Lisp, and is both compiled and scriptable. Of course, it requires contributions to make it usable as a daily driver, but I guess that is somewhat the point. The vision is sound imo.