Replacing Harrison Ford in anything is no easy task, but asking someone to step into his two most popular roles, Han Solo and Indiana Jones, is nearly impossible. But that's exactly what has been discussed over the last few months. Just yesterday we learned Lucasfilm was making the job more difficult by testing more than 2500 actors to play a young Solo, and now Steven Spielberg has chimed in on the possibility of someone else playing Indiana Jones. To him, there can be only one Indiana. He tells Screen Daily...
"It’s certainly not my intention to ever have another actor step into his shoes in the way there have been many actors that have played Spider-Man or Batman. There is only going to be one actor playing Indiana Jones and that’s Harrison Ford."
There has been some back-and-forth whether a new actor could step in to the franchise and keep it going similar to James Bond. Rumors, including some forwarded by Spielberg, hinted at Chris Pratt taking on the role. Producer Frank Marshall recently stated that nobody but Ford would ever play Jones, and Spielberg's statements would seem to back that up.
Of course, there are any number of workarounds here, because Disney didn't buy the franchise for it to simply end when Ford retires. There's too much money in it.