Something 'deeper' than Emacs, or am I looking for a unicorn?

Hey all - I really love emacs as a text editor and environment, but I'm wondering... Does there exist something that is

- More customizable than emacs

- more mature community and 'giants to stand on' (like packages)

- Stronger expected lifespan

- Realistic enough to actually commit to (not like, build the universe, build your OS from scratch)

I'd love to hear if there's anything you've found beyond the Mariana Trench! Will