Depending on what you consider Emacs to be, it is either unlikely to be replaced, has already been replaced, or the concept makes no sense.

Emacs is an interactive Lisp environment that just so happens to have everything you need for a programmable text editor. Text editors are a dime a dozen, and Emacs is far from the only programmable one (although I'm not aware of any with the degree of programmability that Emacs offers). You can find alternatives for pretty much all of Emacs' functions, but you'll have a hard time finding it all in one place.

People have been talking about replacing Emacs itself with another interactive Lisp platform for decades (generally based on Scheme or Common Lisp), but it hasn't happened. I doubt it will. As cool an idea as Lem or Climacs or whatever are, they haven't attracted the user and developer base needed to even begin to approach Emacs' level.

And by and large, Emacs users don't care. We're a small enough group these days that no one is likely to target us with serious malware. We blindly trust Elpa and Melpa and the people who commit code there, and so far it hasn't been a problem. Complacent? Certainly, but that's human nature.