The idea that perhaps Indy would be somehow lost came to me a long time ago.
What if the film starts with newspaper and radio reports stating that Indy is missing.
"We have had news that the world famous archaeologist and adventurer, Henry Jones Jr. is missing. Dr. Jones was last seen leaving for the Amazon Jungle two months ago but nobody has heard anything since his departure. Colleagues and friends are extremely concerned as even though Professor Jones is known to be absent for long periods of time, there has been no contact."
Henry Jones Sr. is out of his mind with worry and Marion, Willie and various other girlfrieds now feel guilty for breaking up with Indy...
Then we go onto a scene where some friends of Indy's go searching for him. We then flash forward to the Amazon where a very dishevelled Indiana Jones is running from something. His hair is tousled, he is covered in cuts and bruises and his clothes are ripped and torn. He stops suddenly (similary as he does in Raiders and Temple) and the camera pans into his eyes, and we are taken back two months before and we find out why Indy went missing and exactly what he is running from.
That part I haven't worked out yet...
Also I would love to see a classroom scene and I have an idea how they would incorperate this into Indy 4. Indy is rescued by his friends, and decides that his adventurous lifestyle is just too dangerous. He rests up and spends time with his father. Some time later with his father and various friends supporting him, Indy decides that he's had enough and he wants to give up the 'adventurous' side of his career and teach. He also wishes to resume his digging career (similar to the beginning of the Infernal Machine).
Indy's friends throw him a semi-retiring bash and there he meets up with several of his old girlfriends. One woman comes up to him and askes him how he is and no sooner has she done that, Willie comes over and kisses him on the cheek etc.
During the party, Indy's father becomes ill and is taken to hospital. There, Henry tells Indy about a dangerous artifact which he knows the location of. Indy is told by doctors that his father is dying, and so Indy must find this artifact as the fate of his father and the world hangs in the balance.
Will Indy survive the treachery he is about to face? Can he survive one more adventure?
Da da da da!!! Da da da....
Well they're just some ideas I've got.
"I don't know. I'm making this up as I go..."