Actually, I have experienced some slight (albeit very subtle) changes. And I can see these changes just by comparing my "guy voice" now versus my "guy voice" in my pre-hormone videos. In the pre-hormone videos, my voice had a lot more of a booming quality to it. It was more powerful. But now, I can't quite match that same sort of power anymore. It sounds a bit softer. And if I speak in my "guy voice" for too long, it starts getting tired.
Again, subtle changes, but changes nonetheless.
In regards to the opening question, about a voice "un-breaking," and going back to the pitch and tone that it had as a child... no, that will not happen. Once the throat has expanded to adult male proportions, which involves lengthening of bone and cartilage, it will not be able to ever go back to the way that it was. The muscles, however, can indeed change. And you can indeed "train" them through vocal exercises to be able to speak in that same range again, despite the deeper range and deeper resonance still being there.