AI can manage its own prompts too. It can write software end to end without human intervention. Other than prose literally what's the use case of something like emacs or vim? Even auxiliary tasks like managing git repos with magit could be done by ai. Everything that can be done in a computer could be done by ai, especially code related or sysadmin related. The only reason to use a text editor is to manage notes, write prose / poetry or manage one's own agenda.