No, that's not the plan. The plan is to replace the Emacs Lisp runtime with a Guile-based runtime.

See here: 'is a branch of GNU Emacs that replaces Emacs’s own EmacsLisp engine with the Elisp compiler of Guile.'

The word is 'ENGINE'. That's the underlying language runtime.

It's neither GNU Emacs right now, nor will Emacs Lisp be replaced.

I thought that project is perennially under development, and at this point in time more like good thing to look at than having a real chance of getting merged with master?

Probably. ;-)