The big question for Avengers is whether it'll become the third film to crack a billion OS. While I wouldn't count it out, I wouldn't say it's guaranteed, either. Part of the problem is that it's not just contingent on retaining or expanding the audience, but also on the exchange rates. A weak dollar could translate to a weaker OS gross, even if admissions go up.
Still, I'd expect Avengers to win the DOM race, even with a 10-20% decline from the first, and WW. Probably something like 500-550 DOM and 900-1050m OS, so something between 1.4 and 1.6b total.
SW7 could hit 500, but that's approaching its ceiling. Even so, I'd probably give it a better chance of winning DOM than winning OS or WW. It's really difficult to peg what the OS gross will be. 600m seems a safe, conservative guess, and as much as 800m is possible, but not much more. DOM is probably good for 450-500. WW of 1.05-1.3b.
I rather doubt anything else will hit a billion.