I think Marvel deserves its own theme park. While the Marvel Cinematic Universe may not last forever, the Marvel characters themselves have proven to have stood the test of time. And Marvel has much more diversity of settings and characters than Star Wars. So think of it less as "a theme park based around one IP" and instead a theme park based upon thousands of IPs that happen to be under the Marvel name.
If done right (with proper planning and a gigantic budget) it could be a very immersive experience.
The most extensive land could be New York City. This area would be the equivalent of Main Street in Disneyland, where you could have restaurants and shops and iconic Marvel locations such as the Daily Bugle. New York could include the Avengers Campus (like Disney California Adventure) and rides themed around Spider-man and the Fantastic Four. Other New York-based Marvel characters like Daredevil, Jessica Jones and Luke could also appear. Maybe there could be an interactive experience where you help Jessica Jones solve a mystery.
Adjacent to New York, you could have SHIELD Headquarters where you could meet Nick Fury, Black Widow, Maria Hill, Agent Carter and Hawkeye. SHIELD could recruit you on a mission in which you ride in the SHIELD helicarrier and have to fight a foe in the sky (it could be a very immersive experience like Rise of the Resistance.)
You could also have Xavier’s Mansion (aka the X-mansion), where you could meet all of the X-men and (through a simulator ride) train to fight Sentinal robots in the Danger Room.
Asgard could be where Disney goes all out with the fantasy aspects of the MCU, featuring mythical creatures. Characters like Thor, Loki, Hela, Valkyrie, and Odin can appear here. There could be dueling roller coasters where one group is Team Thor, and the Other is Team Loki. Another ride could have guests battle the Frost Giants, go to the Dark World, or fight a mythical foe not yet featured in the Thor movies. You can have a Viking-themed dining restaurant. Leading up to Asgard and Thor’s Kingdom is the rainbow-colored Bifrost Bridge, guarded by Heimdall. The bridge could connect to other areas of the Marvel Theme park. I think this land could move way beyond the MCU and feature mythical beings from the comics. Asgard could be the closest to “Fantasyland’ that we get in The Marvel Theme Park.
Of course, there should also be a Wakanda land, where guests can ride a monorail or a tame roller coaster throughout the city and travel through Mount Bashenga, where the vibration is stored. Disney will need to spend A LOT of money to do this land justice, but it could be the most stunning section of the park. A simulated ride featuring giant screens and 3D technology could involve you trying to protect Wakanda (I believe such an attraction has been proposed for Disney’s California Adventure). You could also dine inside the Royal Palace with King T’Challa and meet the Dora Milaje and Shuri. There could also be a stage show centered around Warrior Falls, where we witness a battle for the throne. Maybe a dark ride could tell the story of Wakanda’s history, featuring advanced animatronics.
There could also be a ride in which you enter an advanced-submarine-like vehicle and travel to Atlantis, where Namor reigns. Think a more impressive version of the 20,000 Leagues Under the Sea ride, with all of the advantages of modern technology.
There should be a space-themed section of the park, with thrill rides, restaurants, and interactions with space-based or cosmic marvel characters like the Guardians of the Galaxy, Captain Marvel, the Skrulls, Thanos, Silver Surfer, Galactus, the Watchers etc.
There could also be an area of the park that deals with magic users and the supernatural. For example, you could have a magic show and a trippy thrill ride with Doctor Strange in the Sanctum Sanctorum. Wanda/Scarlet Witch could have a 50s diner (a nod to Westview in the Wandavision show) that appears to glitch (as it’s all an illusion in Wanda’s mind). There could be a ride where you join Ghost Rider on a motorcycle-like roller coaster (similar to the Tron attraction in Shanghai). Finally, there could be a horror-like attraction where you come across demonic characters like Mephisto, Blackheart and Nightmare. Other characters that could be featured include Agatha Harkness, Blade, Moribus, Moon Night, and Werewolf by Night. This land would emphasize thrills and be a bit edgier than the rest of the park.
And Finally, there should be a Villain land, which features many thrill rides and roller coasters. If they do Dr. Doom justice in the MCU, I’d say they could have the villain land centered around his castle in Latveria. There could be a spectacular stunt-filled show in this land where Spider-man has to defeat the Sinister Six.
I know something like this would probably never happen, but I just think there’s so much more potential for the Marvel brand than the relatively small Avengers Campus in California.