There is a suggestion that the story may not be a sequel or a reboot, but instead take place before the other films. This would be one way of recasting the role with a younger actor, without having to actually reboot the series. Whether anyone really wants to see Indiana Jones before the events of Raiders Of The Lost Ark is very debatable, and just the thought of the words George Lucas and prequel is enough to make most fans jump into a snake pit, but its one that is certainly still a possibility.