Marvel is different from Potter, Star Wars, and LOTR in that it is a collective of marquee properties that each drive their own franchises, and then combine into Avengers events. In order to work, it actually needs to pump out multiple movies each year. And it also has fifty decades of monthly storytelling to draw on. LOTR has four novels by Tolkien, which have already been adapted, and lots of notes. Rowling keeps her Wizarding World on a short leash. Star Wars, with the old EU, has a lot of story depth, but Disney abandoned a lot of it (mostly the third generation Skywalkers), and they seem reluctant to tap into stuff like KOTOR and Tales of the Jedi which would open up all kinds of storytelling possibilities.
I still think Potter, in its heyday, was bigger than Marvel is now. I’m looking at intensity of interest and cultural penetration, not box office receipts. A lot of people seem to be going to Marvel movies, but it seems like the fanbase is more casual, and people don’t live and breathe Marvel like they did Potter and Star Wars.
Merchandising is also another area. Star Wars once ruled here, but the last few years have a seen a catastrophic drop in interest in the merch. TFA and RO action figures still pegwarm at Walmart, and it doesn’t look like they’re even stocking Solo toys. I don’t really see a lot of Marvel merchandise in stores, looks like Walmart gets a case of whatever action figure wave comes out, and there are posters and insulated tumblers, but it doesn’t seem to move a lot. Again, Rowling seems to keep her franchise on a short leash; in stores I see mostly trinkets like Hogwarts house related keychains and the like (and the stuff usually looks picked over at Target, with Slytherin stuff on the mostly empty pegs), and more high-end collectibles at Barnes & Noble. Tolkien stuff is rare, only seeming to appear when there’s a movie. (Saw a nifty-looking “Sorcerer’s Stone”-inspired chess set there the other day I almost picked up.)