(c) Emacs won't disappear after a few years (where "few" can mean decades if your career lasts that long - mine ran from 1967 to 2011 and I still use emacs daily) the way virtually every (or maybe every) "more intuitive" editor/environment will, given time. Your investment in learning it will really pay off.
Adoption rates of intuitive IDEA and Visual Studio, while not quite as old, have long pushed Emacs into niche territory. Emacs hasn't disappeared only in the sense any venerable UNIX utility hasn't.
"hasn't disappeared only in the sense any venerable UNIX utility hasn't"? "Only" doing a lot of work here! That's the most reassuring "only" I've read all day. I bet you a pound people will still be using Emacs in 2050.
Though all of that, I have used GNU Emacs, definitely an unconventional choice for Java development. I've occasionally tried the leading IDE, and while it's sometimes been helpful to ramp up on new projects with tools shared with other teammates, the productivity of a comfortable and customized Emacs environment has always drawn me back.
In 10 years, IDEA and VS may or may not be still widespread, but Emacs will definitely still have its niche.
Not to say that you should use Emacs instead of VS Code or anything else. Just that Emacs not disappearing means that your investment to learn it and set it up is more likely to keep yielding returns.
If existence is tantamount to corporate sponsorship, then GNU Emacs never existed. It'd take one or two graybeards with too much free time to sustain Atom. Just look at the current Emacs maintainers.
What do you mean by this? The emacs-devel list looks like a smart and generally well run project.
Perhaps. Does Atom have said graybeards? The motivated ones are hard to come by.
What makes it worth it for me is that
(a) Once configured properly, I have a uniform interface to files, regardless of what sort of files they are. This save me time and mental effort.
(b) Emacs is extremely hackable in ways you won't understand for the first year or two, at least. If there's something about its behaviour you don't like, you can run a couple of commands and be taken to the relevant parts of the editor (Lisp) source code. Then you can replace that code (or better, write new code that hooks into it dynamically) with whatever you would like instead.
The latter sounds like a nutty thing to desire, and it's very hard to appreciate it without having used it for a while.