While I was in Austin for Butt-Numb-A-Thon it was announced that Paramount and Disney had reached a deal that would give Disney the rights to release new indiana Jones movies. This is a bad idea, but it'll be a profitable one - as so many of Hollywood's bad ideas are.
If Disney struck this deal we must assume that they want to make more than one Indiana Jones film. Clearly they'd like to get this franchise up and running again and probably crank out at least a few more. The problem here is that Harrison Ford is old and just keeps getting older; while he's in better shape than many of us could hope to be at 71 it's hard to imagine him still having what it takes when the third film in whatever new trilogy Disney envisions comes out in ten years. Indiana Jones was initially intended to be the American James Bond, and that would make you think we could just replace Ford with another actor as has been done with Bond many times, but I don't think that would work. Audiences identify Ford with Indy completely, and just throwing another guy in the hat ain't gonna do it.
You could, if you wanted, have Old Indiana Jones telling a wraparound story for a movie that introduces a new, younger actor in the role. Old Harrison sits in a chair - as in the Young Indiana Jones Chronicles - and spins a yarn, which makes up most of the movie. But I don't think Ford wants that; he's made some noise about wanting to play the role again and this doesn't seem like it would satisfy him. Still, you can't have 81 year old Harrison Ford playing Indy in the era of Austin Powers.
But what if you take that concept and expand it? What if you have Old Indy, still in the 50s milieu of Crystal Skull, involved in an adventure that turns out to be a continuation of one he had in his 30s? Instead of having a wraparound you jump from era to era in order to tell one story, with the same MacGuffin as the object in both time periods. Think The Godfather Part II, excpet instead of flashing back to Vito Corleone we're flashing back to Prime Time Indiana Jones. You cast that younger Indy well and then Indiana Jones 6 can totally take place in the 1930s, with Old Indy happily and respectfully shuffled off.
Or we could have three more films with a rapidly deteriorating Harrison Ford in the lead. Better yet we could have no more films, but I'm aware we live in the darkest timeline when it comes to over-exploitation of beloved properties.