Not exactly new info here, but good info nonetheless.
Keeping Harrison Ford's advanced age in mind, here is my take on the plot for this fine film:

Indy must find his petrified prostate before Hitler does and uses it's mysterious powers to achieve immortality, thus cementing Germany's position of power and ultimate victory in the second world war which for the purpose of our story dragged on well into the late 1950's.
Of course Indy must contend with a spunky, attractive younger woman who's father was kidnapped by the axis powers and is being held captive and forced to decipher the mystery of Jones' aforementioned prostate.
At the same time, there is an equally spunky young asian sidekick who keeps getting into trouble, requiring rescue after rescue.
Sallah is now retired and living a life of luxury and domestic bliss with his seven wives and thirty two children and must come out of retirement to help his old friend Indy once again. Unfortunately, his colostomy bag slows him down, so he must decline.
Dr. Henry Jones (Indy's dad) does not appear in the film as Sean Connery had an argument with Spielberg about the fit of his wig and knocked him out before storming off the set.
Marcus is still the curator of the museum at the university Indy teaches at (where despite Indy's advanced age, the college girls still swoon over him), but is bound to a wheelchair ever since falling off his horse at the end of the last film as they all rode off into the sunset. He has since suffered a stroke and has a tendancy to drool when he speaks.
With all this going against him, will Indy be able to save the day? Will he ever see his father again? Can he rescue the captive scientist? More importantly, can he sleep thru the night without having to get up and pee sixteen times? All these questions and more will be answered in: "Indiana Jones and the Quest for Lost Youth". Coming soon to a theater near you.

Seriously though, from what I understand, they will be treating the age issue as one of the main themes in the movie. Such as Indy's inability to adventure like he used to and his dealing with the knowledge. Also from what I have read, the current treatment calls for a supernatural storyline. In all honesty, Spielberg, Lucas, Ford, Connery, let's face it, I'll be there on opening night to see this flick.

I wish they had continued to do some Indy Jones films. I have all of the YIJ shows on videotape too. He was such an interesting concept to me.

I think a new one with him getting older is an excellent idea as long as they play up the fact that he IS getting older and deal with it. I saw that "6 days, 7 nights" flick he did with Anne Heche a few years ago and he looked pretty damn amazing for his age so I have no doubt that he'd be fit enough to play it. There's a lot of mileage to be had out of the realities of the toll Indy's lifestyle has taken on him. As always, they can do anything they want as long as they do it WELL.

Do you think that maybe something of a plot where he hands off the "family business" to his son or even a daughter would work?

Eh? What's that?