I think that with Iron man fans, thor fans, Loki fangirls, Cap fans, hulk fans, scarlet johanson fans, comic book fans and disney's name on the film this is going to be no 1 in the box office that year
Not a chance.
Like Kang mentioned above, it could easily become #3 for 2012 behind TDKR and The Hobbit; but I could also see it battling hard for that 3rd spot with Spidey Redux and the Twi-Tweenies saga. (And I still look for Prometheus, MIB III and Hunger Games to be the sleepers....any one of those could break out to surprisingly huge numbers.)
I *am* curious to see what Disney's marketing strategy will be for the movie, though. I'm betting that one of the things they'll do different from Marvel Studios' marketing campaigns is that they'll lay off the 30-second snippets and teasers that practically revealed the entire plots of all the Marvel movies before....I think that Disney, instead, will rely on a coupla three really epic theatrical trailers and one or two promo scenes for the talk show circuit, and that's it as far as footage reveals.
Well, there was Alien vs Predator. I don't know how well that did.
Also, back in the 70s, I don't seem to recall whether there were two separate movies starring Dustin Hoffman and Meryl Streep respectively, both called Kramer, that were combined into the Oscar winning movie, Kramer vs Kramer.
No to Kramer vs. Kramer, but there's also been Freddy vs. Jason, the CSI shows, Law and Order, Doctor Who, Stargate, Star Trek, Hercules and Xena, the Happy Days spinoffs, Who Framed Roger Rabbit?, and most of the Kevin Smith movies. Characters cameo and walk-on VERY often in TV shows that share the same producer(s), so you have "shared mini-universes" for everything from Cheers to Friends to Magnum PI and Everybody Loves Raymond. In olden times, crossover characters were *very* common in cheap horror flicks (Frankenstein Meets the Wolf Man, Abbot and Costello Meet Frankenstein, Frankenstein and Dracula Meet The Fockers....well, maybe not that last one) and all the Godzilla kaiju films.
Also, Whedon himself has also dabbled in crossover characters and plots between his Buffy and Angel TV shows. Plus, you've seen all-star ensembles from fiction in
The League of Extraordinary Gentlemen and the old murder mystery spoof
Murder By Death.
Also, google Richard Belzer as Detective John Munch. He *is* Teh Crossover King.
Crossovers are extremely common. In everything from movies to TV to video games to comics to anime. That's why I don't know why people make The Avengers out to be a big deal, or "TEH FIRSTEST," when it's nothing of the sort. We all know that the Marvel Universe has *always* been a shared universe...it's just taken Hollywood fifty someodd years to catch up with us.