I liked the premise of this book and I found the overall argument to be both interesting and, with some exceptions at the end where Jenkins tries to provide a voice for the future, persuasive.
What follows is not a review of the book, it's an observation.

If you're writing a book about popular culture, even for an academic audience, you might want to assume that some of your readers--while probably also academics--are what one might call huge nerds. Not that you have to write "for" them, but you should account for that and remember that we take our genres no less seriously than academic scholars and the difference between getting our canonical information wrong and misattributing a Shakespearean quote is one of degree, not kind.

1) It's spelled Gandalf, not Gandolf. Gandolf is the name of a priest in Robert Browning "The Bishop Orders his Tomb at Saint Praxed's Church" (and last year's January winter storm, for reasons still unknown). Gandalf is the wizard in Lord of the Rings.

2) Ewan MacGregor did not play a young Qui-Gon Jinn, he played a young Obi-Wan Kenobi. Liam Neeson was Qui-Gon Jinn.