I would just like to say that these are my personal beliefs, and they don't mean anything YET. If you don't want any spoiler, stop here.

In the audio excerpt of Sacrifice, Mara states that she is going to finish what Luke started, meaning going after Lumiya. This could mean that Luke is predisposed. On the back of the book, Luke seems to be frozen in a stance. I believe that either Lumiya or Jacen will put Luke in Carbonite freeze, because of this evidence. Any other fan speculation?