I like emacs because it is essentially a operating environment for a
lisp variant - elisp and therefore pretty much infinitely extendable since
elisp is a General Purpose Programming Language.
elisp isn't a lot of fun to code in tho, it's not as modern as newlisp.
Vim has been developed with 'hooks' so that one can embed a number of
interpreters at compile time. This means that when you are running vim,
you can also be running python, perl, ruby, tcl, csope, netbeans etc.
I have no doubt that newlisp could be embedded in the same fashion.
It would then enable the user to extend the Vim system using newlisp code.
I believe it would take some coordination between Lutz and Bram Moolenar, who is the developer of Vim.
It is likely that Lutz would find Bram very approachable.
My .2 cents worth.
tim