One of the major unresolved issues from Star Wars: The Last Jedi is what will happen to Carrie Fisher's General Leia. The novelization of the film does give us an indication of where Leia may leave things with one old friend. At the end of the movie, we see Leia escape on board the Millennium Falcon with what's left of the Resistance. The novelization, however, includes an additional scene where Leia, grieving the loss of her brother, turns to Chewie, one of the only other characters left who started the adventure, and says...
Having lost Han Solo in Star Wars: The Force Awakens and then Luke Skywalker in The Last Jedi, we're down to just those two of the four main characters of the original trilogy. Of course, the words, which were revealed by a fan on Twitter, are even more heartbreaking, as the reader knows that, one way or another, when Star Wars: Episode IX comes along, we'll lose Leia as well, leaving only Chewbacca as the last hero standing.
There are a couple other important characters from the original trilogy who are also still around, in C-3PO and R2-D2, though they haven't been nearly as important in this trilogy as they have been before. It will be interesting to see if they become bigger characters in Episode IX due to the lack of other familiar faces.
Novelizations of movies are always interesting as they require that the story go a little bit deeper than the film that inspired it. We often get additional dialogue or characters' internal thoughts, which help to explain motivations. While these books are not necessarily canon, they still provide new angles on the story that fans will be interested in.
Of course, this fact also makes the eventual novelization of Star Wars: Episode IX a potentially interesting artifact. Since Disney has claimed that they won't be using CGI to recreate General Leia in the next film, that means we won't see her at all in the new film, but that doesn't mean that we won't see her again in the next book. Whatever explanation is given for her absence in the movie could be elaborated on in more detail in that book, or another novel that is planned to tell that story.
Of course, exactly what happens to her will depend in large part on how much time passes between these final two episodes. While previous Star Wars movies saw years of in-movie time pass between installments, The Last Jedi broke with tradition by picking up immediately after The Force Awakens ended. Episode IX could follow suit or it could go back to the previous standard and see a long time pass between films, meaning the possible scenarios are essentially limitless.