In fact, the vast majority of them will be returned, unopened, to sender. There are good, hard-nosed reasons for all this. First and foremost, to be blunt about it, most of the unsolicited submissions are no good. Based on what I have heard from editors, and have seen for myself, I can tell you that most of these submissions are badly written, or based on a bad idea, or formatted improperly, or inaccurate or careless about the known facts in the universe in question, or just incredibly sloppy. Some are written by people who, judging by their writing, appear to be deranged.
People obsess on some favorite character from the movie.
In other words, even if your unsolicited STAR WARS novel is an absolute gem, it is likely to be quite literally buried under a mountainous heap of unpublishable gibberish. It's going to be literally in the same pile with all the nut manuscripts, and will be lumped together with them. Let me try and explain by example. The book gets to Editor E, who reads the book, decides it's no good, and rejects it. Fervent Fan F decides that Franchise Z has stolen his idea of X getting married.