With Indiana Jones and the Kingdom of the Crystal Skull having earned a massive $743.7 million worldwide (#27 on the all-time worldwide list), The Sunday Times asked George Lucas if he, Steven Spielberg and Harrison Ford would be up for a fifth film:
“We were hoping for box-office figures like that, which is, ultimately, with inflation, what the others have done, within 10%,” Lucas explains. “So, we squeaked up there. Really, though, it was a challenge getting the story together and getting everybody to agree on it. Indiana Jones only becomes complicated when you have another two people saying ‘I want it this way’ and ‘I want it that way’, whereas, when I first did Jones, I just said, ‘We’ll do it this way’ — and that was much easier. But now I have to accommodate everybody, because they are all big, successful guys, too, so it’s a little hard on a practical level.
“If I can come up with another idea that they like, we’ll do another. Really, with the last one, Steven wasn’t that enthusiastic. I was trying to persuade him. But now Steve is more amenable to doing another one. Yet we still have the issues about the direction we’d like to take. I’m in the future; Steven’s in the past. He’s trying to drag it back to the way they were, I’m trying to push it to a whole different place. So, still we have a sort of tension. This recent one came out of that. It’s kind of a hybrid of our own two ideas, so we’ll see where we are able to take the next one.” (From ComingSoon.net)