That's what this project is working on: https://github.com/carlosdcastillo/vim-mode -- using neovim as the editing backend to Atom. It still doesn't completely solve the problem of vim and editor key commands clashing.
Another interesting approach is VimR (http://vimr.org/), which is Neovim combined with native IDE addons such as Markdown preview, file tree, etc. The nice thing about VimR is since the whole thing is one cohesive package, the developers can ensure it has a consistent experience. Sadly it's OSX only though.
This is basically what the language server protocol (https://github.com/Microsoft/language-server-protocol) is doing, just in reverse.
The obvious example would be using the neo-vim frontend to interact with VSCode, Eclipse, IntelliJ, etc.
What I want most is a Neo-Vim frontend to org-mode in Emacs, because it would be hilarious and because while Spacemacs is kind of cool it's still not Vim. And org-mode is awesome and unparalleled but vim > emacs all day.