I'm bored... Read and post your thoughts.
According to everyones favorite columnist, Jim Hill, the two Pirates will most likely have a cost of around 600 million. This seems rather reasonable for the additional shooting, the advertisements and the printing of the two movies (something that can cost a lot, see Van Helsing).
Now the sequels can go several ways. It can go the Lord of the Rings way where each sequel makes more than it's predecessor. So I would guess 315-330 for Dead Mans and 330-350 for End of the World (if Disney can push out the DVD of Dead Man's Chest during the Holiday Season to increase demand).
The sequels could also pull a Matrix. Where the second will do well regardless but it leaves such a bad taste in the audiences mouths that no one bothers with the third. This happened kinda with Star Wars but with the 2nd doing meh (by meh I mean 310 million...).
Mr. Hill likes to freak everyone out... He stated that he was a little worried about the 600 million Disney and Jerry dropped for the two films. Seeing how the first made 654 million worldwide, I have no doubts the 2nd will make that if not seven hundred in world receipts. So barring a complete disaster (think World War Three, comet into DC) the third movie is pretty much a freebie. I can see people getting iffy about making the six back here in the states, but seeing how 53% of the income for the first came from around the world, I doubt Disney cares much about the 575 the two would make here with worst case scenarios.
My guess, Dead Mans Chest will open at 95-105 million and finish with 315. End of the World's domestic money relies on Dead Man's Chest boxoffice kitty and word of mouth.
Sources = Boxofficemojo.com