This suggests that copyright isn't holding back these works...
IF the copyright holders are kind enough not to harass those fans for infringement. And this kindness is quite commonplace in some contexts (people writing stories about their favorite literary characters rarely get cease-and-desisted), but much less in others ("fanfic" movies about Mickey Mouse are a no-go even for free).
The Lord of the Rings is sorta-kinda fanfic to Beowulf, the Witcher is fanfic to Slavic and Celtic mythology. Neither of these two authors started as "big published renowned authors", they were both amateurs smitten by some earlier works.
And yes, I realize again that in those particular examples, the original work was no longer protected. But that is irrelevant to the question of the derived work's quality.
It could potentially help theater owners, who provide a somewhat unique experience. That doesn’t seem very valued these days, though.
Actually, it seems surprising they haven’t moved into sports (especially with sportsbooks becoming so popular).
For example the 2024 Summer Olympics, with NBC owning exclusive rights to the US market for video coverage (meaning NBC Universal, meaning Comcast) IMAX licensed the opening ceremony to be picked up from NBC and delivered to their US cinemas over IP with fixed latency. It was only the opening ceremony and no scored events. That involved NBC, IMAX, and LTN to carry the video in between. IMAX and NBC negotiated the rights and LTN got statements of agreement on that from NBC. There was involved planning and engineering work to make sure the technical part went smoothly. I'm sure the negotiations, contract writing, redlines, and final sign-off between the source and destination took longer than the tech work.