In a shocking turn of events, Lucasfilm has released a statement saying that Colin Trevorrow is no long going to helm the ninth film in the Star Wars saga. Their statement recited, “Colin has been a wonderful collaborator throughout the development process, but we have all come to the conclusion that our visions for the project differ. We wish Colin the best and will be sharing more information about the film soon.”
This is interesting news that stirs up a lot of speculation; Especially after the firing of Lord and Miller from the standalone Han Solo film. Perhaps Lucasfilm assumed that Trevorrow was not the right man to take over the project after the box office and critical failure of The Book of Henry. Apparently it had to do with the script as well after Lucasfilm brought playwright Jack Thorne aboard to polish up the script.
This is clear speculation, but it wouldn't be shocking if Rian Johnson ends up being the one to take over the film after Disney has expressed their satisfaction with the The Last Jedi and how much of a pleasure it's been to work with him.