Sean Connery wasn't cast in Indiana Jones and the Last Crusade as a lark. That casting was a wink - Steven Spielberg officially made James Bond into the father of Indiana Jones. Indy was born when Spielberg and his pal George Lucas were talking about movies they wanted to make and Spielberg lamented how badly he wanted to do a Bond film. Lucas told Spielberg he had a character 'better than James Bond,' and so was born the collaboration that would bring us Raiders of the Lost Ark. The structure of that movie was a nod to Bond films, with the movie beginning as Indy finished another adventure, and while Bond and Indy are very different, they're both masculine ideals that represent their homelands' best (and sometimes worst) attributes.
As the film series went on Indiana Jones became just as episodic as Bond; just as you could jump into the Bond series anywhere you could, until Kingdom of the Crystal Skull, leap right into Indiana Jones with little regard for continuity. It sort of makes sense that the best way to continue the adventures of Indiana Jones would be to recast him, as EON has done for decades with his inspiration, 007.
That, for some reason, is not the plan.
“We’re not doing the Bond thing where we’re going to call somebody else Indiana Jones,” producer Frank Marshall tells Total Film. Of course that doesn't mean they have a big plan in place. “We haven’t even sat down to talk about Indy yet… at some point we’ll sit down. But there’s a bunch of people who could probably take the baton.”
Nobody tell Marshall that 'taking the baton' was the plan with Kingdom of the Crystal Skull, and look how that went. Also, nobody tell Marshall that the appeal of Indiana Jones is that he exists in a very different kind of world, a world that is contemporaneous to the pulp magazines that inspired so many of his adventures. And definitely don't tell Marshall that we pretty much like Indy best when he's up against Nazis.
To be honest, what these quotes tell me is that nobody inside the world of Indiana Jones knows what they're doing with the series now. They are doing something - everybody is on the same page about that - but what that something is remains almost totally up in the air. I respectfully direct Frank Marshall to a piece I wrote two years ago, about how the only way to do a new Indy movie/reboot is to structure it in the The Godfather Part II style, with action in the past commenting on and reflecting action in the present. The young Indy you cast in that film will then break out into his own adventures, while Harrison Ford gets one last go-round in the hat and retires gracefully. That's your baton hand-over.
But I know what you're thinking. You're asking the real big question: does Colin Trevorrow direct the first new Indy film or one of the sequels?