I suspect that at some point, another editor, inspired by emacs, will
possibly replace emacs. Maybe it will use guile, common lisp or some
other extensible scripting language with more power than elisp. maybe it
will be designed form the ground up with support for all those things
now considered important that were not even on the horizon when emacs
was first being designed. This isn't a problem and to some extent is
just natural evolution. However, I can't see this happening for a long
time - it would take a lot of work to create a new editor from scratch
that had the power of emacs, but its not something to be feared. Rather,
its something to be embraced!
I sometimes think Eclipse is that editor. Of course it misses one of Emacs' strengths in that extending it is a rather heavy-weight process. This distinguishes it from systems like Emacs, SmallTalk, Oberon, which blur the line between development tool and platform far more than Eclipse manages to.
Until then, I'll continue to use emacs as the only editor I use and I
use it at least 10 hours Mon-Fri and a good 6+ hours sat and sun. If a
better alternative comes along, I'll adopt it. Until then....
Here too, along with Eclipse (with Emacs keybindings).