Ask HN: What is to Emacs as Neovim is to vim?

There are several attempts -- some more, some less successful -- to refactor, improve, and extend Emacs as a platform and editor. (One of the more interesting ones, in my opinion, is GuileEmacs, which is an attempt to use Guile Scheme as a replacement for Emacs Lisp.) Here is a good list of things you might be looking for:

http://www.emacswiki.org/emacs/EmacsImplementations

You mean, vaporware, or some other interpretation?

You have a funny definition of vaporware. There's active work happening in public in the neovim repository, and a summary of the work to date here: http://neovim.org/news/2014/june/

XEmacs perhaps? I remember it being purported as "The Next Generation of Emacs" years ago.