The movie is a $100 million plus bet. It’s going to need to succeed on its own merits, any tie-in RPG products will be pulled by the movie, not push it. To be successful they not only need everyone who plays D&D to go see it, but to bring 10 friends.
Sort of like the Guardians of the Galaxy movie it’s being compared to, that movie‘s revenue dwarfs the sales of the comics by orders of magnitudes.
D&D has more of a presence than Guardians did before the movie, but even if it’s the cultural presence of say Spider-Man before Sam Rami, it’s a huge leap from selling 100s of thousands of books per year to getting 40 million people to go see your movie.