Note: This post is an assumption based on info known or leaked.
After seeing the Taral V flashpoint (Thank You, Jaevyn, I had not seen that before) this is starting to make a lot more sense and the book seems better.
For those who had not seen the Taral V flashpoint, please see it here:
I believe the force ghost in the video is the Exile. What we know so far is she dies and turns into a force ghost. When she is talking to Master Oteg she mentions a prisoner, this prisoner is most likely Revan. She says he has been imprisoned for 300 years and is extremely powerful. After doing some research I found other discussion threads regarding this topic.
A user in the thread (Page 2) says he read the book and at the end Revan and Lord Scourge are kept alive by a Sith Alchemy technique only the Emperor knows, I would assume it also keeps them from aging (Scourge leaked pictures). I think this means that the Emperor had imprisoned Revan alive to consume his power and Lord Scourge ties in with this as he is a Jedi Knight companion. So I think Revan is not dead, and it's the players (end game content? since Taral V is only a level 32 dungeon I don't think Revan will be rescued) who rescue him.