Something like Lem[1][2] could go even further because of the richer CommonLisp ecosystem compared to Elisp one. [1] https://lem-project.github.io/ [2] https://github.com/lem-project/lem
Lem is great and I'm happy there's finally something out there to challenge Emacs' hegemony, yet pragmatically, unless someone builds a way to run Elisp in Lem, it's unlikely to overthrow Emacs anytime soon, and that's just not gonna happen.
Org-mode, Magit, and thousands of packages aren't just "Elisp code" - they depend on Emacs' specific buffer model, text properties, overlays, markers, the display engine, process handling, and countless quirks packages rely on (intentionally or not). A Lem Elisp interpreter that didn't also reimplement all of that faithfully would run trivial `.el` files and choke on anything real. At that point you've reimplemented Emacs inside Lem.
Elisp is not the biggest point here and Neovim proves that with pivoting to Lua; the crux is the runtime and the corpus, and reimplementing those is the actual mountain. That is real ecosystem for whatever reason you're choosing to simply ignore.