In regards to the Demonreach knowledge, I'm hoping he incorporates some of that into his new shield bracelet, which we may see in PT.
In regards to shapeshifting, he probably won't have time to sit with L2W until after PT, but maybe L2W will make another appearance at the talks and they'll make plans.
In regards to the WK mantle, I think he's still got more to explore. I'm hoping we'll see him come to terms with it in PT so we can proceed further with his growth.
In regards to ghosts, I'm hoping that Fitz's ability to hear them is an aspect of Listening, something Harry can do. He might have to learn a new way to do it, but then he can talk to Sir Stu and others, which would come in handy for spying and the like.