Let me make something perfectly clear: I am NOT a fan of musicals! I can count on one hand how many I've enjoyed...with multiple fingers left over. That being said, I'm kinda curious about this.
Did you know "Back to the Future" has been performed as a musical in London's West End since 2021? If I knew, I completely forgot. It was actually named Best New Musical at the 2022 Olivier Awards! Now it appears the show will cross the pond for a Broadway opening sometime next year.
As far as I'm concerned, the only characters that need to sing are Marty McFly and, of course, Marvin Berry and the Starlighters at the prom...just like in the movie. (Fun fact: Marvin is Chuck Berry's cousin!) No songs for Doc, George, Lorraine, Biff, and certainly not for Mr. Strickland!!!
I'd consider making an exception for Needles who was played by Flea from Red Hot Chili Peppers, but he didn't show up until the second movie.