Well depends what you are calling "live rock" if you simply mean covered in bacteria and to deal with the nitrogen cycle, then hell you don't need any LR to start with. If you mean filled with a bunch of microfauna, then your dry rock might turn to live rock, however more likely than not you'll have very little diversity. However over a long enough time that'll occur naturally in your closed systems with nothing but LR to start with.
So the question should be what do you want? All dry rock will turn "live" for bacteria, you'll get coraline algae covering it (assuming parameters are right), and corals will grow on it.