Which direction do you see things going? I personally feel that more effort is being put into eclipse, hence it has a longer term future.
A big win for Eclipse is the ubiquity of an easily installed, strong, consistent virtual machine across OSes. Cygwin is a great achievement but too much like hard work. I'm compelled to use Windows in my day job, with no admin access, and being able to use the same development environment with my linux box at home is great.
If you do anything in Java, people will ask for Eclipse integration. Clearly the market has spoken in Java-world ;)
Emacs is good because people who are "good at Emacs" are good at text-editing in general. The tool is more general, but that means they can maintain the majority of their output speed in a new language, or a language where things like automated refactoring are tricky or impossible to reliably do (say, Ruby)
BTW: I'd say "easily installed, strong, consistent" applies more to text editors than IDEs. Emacs has a windows binary thats pretty reasonably sized, whereas Eclipse is in the hundred megabyte range and Visual Studio (insert chuckle here).
A big win for Eclipse is the ubiquity of an easily installed, strong, consistent virtual machine across OSes. Cygwin is a great achievement but too much like hard work. I'm compelled to use Windows in my day job, with no admin access, and being able to use the same development environment with my linux box at home is great.