> Forking is easy. Maintaining a fork, keeping the quality and innovation alive, and the community involved is hard.

LibreOffice is doing pretty well compared to OpenOffice:

* https://news.ycombinator.com/item?id=37645160

EGCS was eventually merged back into GCC (or rather it became the new GCC?). I don't pay attention recently, but XEmacs was/is pretty active along with Emacs.