2). I think you'd be surprised to find out that a majority of Disney theme park guests ARE Marvel fans. Given the huge success and box office records, I wouldn't be surprised to find out that the majority of the American population in GENERAL are marvel fans. Hence, why Marvel Superhero Island has been one of Universal's most successful and popular theme park lands/attractions since it first opened, and why they won't back down on the rights.
3). In 10 years, the same crowd level as RNR would be pretty high up there, so we agree on SOMEthing. So yea, once the "buzz dies down," it'll still be holding an hour/hour and a half worth of wait time. Maybe more considering, again, Epcot has no thrill rides.