Nobody knows better how to milk a franchise until it's creatively bankrupt than George Lucas. Having driven "Star Wars" down the wormhole of prequels, animated spinoffs, video games and more, taking it straight into oblivion, it seemed the Indiana Jones franchise was next on his list. As if enduring "Indiana Jones and the Kingdom of the Crystal Skull" wasn't enough, last fall Steven Spielberg revealed that Lucas had sort of cracked the nut on a fifth movie, figuring out what the MacGuffin would be, but hadn't yet put the story together. But it seems that's as far as it will ever get.
Chatting with Collider, producer Frank Marshall said that 'Crystal Skull' was likely the last time Indy was going to crack the whip. “I say, for me, [Kingdom of the Crystal Skull is] the last hurrah. I know that yes, we talk about it, but there’s no idea, there’s no MacGuffin,” he said, contradicting Spielberg's comments.
As you might remember, George Lucas announced earlier this year he was stepping away from LucasFilm to focus on making experimental movies in his garage (or something). Spielberg's longtime producing partner (and Marshall's wife) Kathleen Kennedy has replaced him on the board, and that's another indication he's done with Indy. “Yeah, no he isn’t [hungry to do another Indiana Jones]. And he’s obviously passing the baton to my wife, so..." Marshall said.