Exactly what's going to happen in Star Wars: The Last Jedi is a closely guarded secret that we don't expect to have spoiled before December. However, there are a few things we can learn from knowledge about what doesn't happen. In this case, that means information about two characters that will not share the screen. Andy Serkis was recently asked about the passing of Carrie Fisher and while the actor had wonderful things to say about her personally, he revealed that he did not film any scenes with her in the upcoming movie. According to Serkis...
Supreme Leader Snoke had minimal interactions with other characters in Star Wars: The Force Awakens. Snoke spent the last movie very much playing the part of the power behind the throne. If Snoke and Leia did cross paths at any point in Star Wars: The Last Jedi it would certainly signal a major shift for Snoke within the plot. However, if you were hoping to see more from the mysterious figure, the odds of that were just reduced.
In Star Wars: The Force Awakens Leia blames Snoke for turning her son to the Dark Side. While we don't know the details, we're sure that Leia would love to confront Snoke over this. For that reason, it's unfortunate that we won't get a scene between these two, as it would have been great to see Leia go after the one she blames for the destruction of her family.
All indications are that the new film will include an attack on the Resistance early on in the story. When that happens we assume that many of the characters will scatter, meaning we have no idea what direction General Leia is going, but apparently we know where she won't end up.
While we don't know what Star Wars: The Last Jedi actually has in store for Supreme Leader Snoke, it sounds like it might be more of what we got before. When talking about the actors he did work with to The List, he only mentions, by name, the same actors we saw him share scenes with in the previous film.
It sounds like Snoke may continue to work in the shadows, only dealing with Kylo Ren and General Hux throughout Star Wars: The Last Jedi. Andy Serkis does mention "the cast" which would seem to indicate others that we shared scenes with, but without calling them by name, he could be simply talking about extras and people with very small roles.
So now we have new information on something that won't happen in Star Wars: The Last Jedi. If you're curious about what will happen, check out everything we know about the next Star Wars movie.