They don't even need Marvel to be honest. Star Wars Land is about to explode into more than Disney will be able to handle. Crowds are already way up over what they normally are, because of Pandora. Then TSL will make it insane, and SWL will make it unbearable. There's only so many Fastpasses you can give people before both queues become backed up to the parking lot.
Whoa, man, dial back the hyperbole a little. TSL isn't going to make DHS crowds "insane". Pandora may have moved the attendance needle a little, but there are few, if any, people visiting WDW solely due to Pandora's opening. SW:GE will have its own challenges when it comes to managing crowds. But this is all due to a decade of theme park negligence in the swamps.