I think 1.5 billion will be the new billion, as inflation always permits. TDKR won't come close internationally, but might put a scare domestically in terms of ticket sales. Then the Hobbit, which will be massive. Eventually Avengers will have company. Like Avatar, Star Wars, ET, Phantom Menace, Lion King which put up remarkable figures, only time will tell if Avengers did enough to separate itself from the pack for years and years.
Well the truth is none of these records lasts very long. Spider-man 1 had the record for 4 year, Pirates of the Caribbean had the record for 1 year, Spider-man 3 had the record for 1 year, The Dark Knight had the record for 3 years, and Harry Potter had the record for 1 year. So really, who the hell knows?
Eventually someone will break the Avengers record, as to when, who knows. I think it's got enough to last at leas this year. The Hobbit will likely have a 3 hr run time which will set it back, and TDKR has a 3 hr run time plus no 3D pricing. It may be Iron Man 3 that sets the record as this is shaping up to be much bigger in scope than Iron Man 2 was, which was somewhat of a letdown to some. We'll know more this weekend.
Iron Man 3, Avengers 2, TASM 2, Hobbit part 2, MoS 2, Avatar 2. These are the most likely candidates if the record will be broken soon.
However here's the thing no one is taking into account. Inflation is one thing, but with Avengers we saw theaters hitting critical mass, which they may do again for TDKR. The biggest obstacle to breaking any new records is the theaters. They are just big enough to meet demand for these huge tent-poll movies, and they are often times too big, through much of the season when movie going is light. What I'm saying is, there no demand right now to add new theaters or add more screens to existing theaters. Even IMAX screens will grow some, but I think the expense of adding them doesn't always pan out in terms of sales. Only for a few select films.
We've literally gone from a system when I was a kid with Star Wars, where the theaters were so small, people were lined up around city blocks to get a ticket to a show, to a point now where with the internet, and the number of theaters close to people, with multiple screens, you can see any movie you want to on opening day.