Based on Inception... around 900 - 900 and it would be cool it could cross 1 billion.
Christopher Nolan's 2014 grand scale science-fiction story about time and space, and the things that transcend them.
Tough call at this point, but if it gets Avatar popularity buzz (obviously will be better quality wise) then it could get near a billion. It's gong to be an event film and Nolan is reaching Spielberg level with general audiences. Without having seen the first trailer and how they market it, I'll guess 800 mil at this point. 65 mil opening weekend.
I think it will do really well, and I love for it to break records, but even with the buzz I'm sure it will get, I think it's going to be hard to break the billion-barrier without a pre-existing franchise or the extra 3D money. Hoping that I'm low: