Seems to be going quite slowly. However, I would think getting a good Scheme implementation as the Emacs default is probably the single most important feature. All Emacs is, after all, is a Lisp interpreter.
Emacs users and developers would continue to write Elisp. The difference is that Elisp would be running on the Guile VM, which will improve performance and bring some features that are currently missing from Emacs (threads, and some other stuff that I can't remember).