There is a nostalgia factor in my wanting to see Harry do one more IJ movie and another reason is the hope of doing something better than CS. We all can see how CS could have been better.
So CS could be left in the past as a product of its... whatever decisions they were.... and an Indy 5 could be a good treatment of an older Indy. I find it hard to say 'old' Indy as Harry is not an 'elderly old', as Kernunnos put it.
The action element would have to be adapted to a level of believability but that doesn't mean lost completely. It could still be exciting and cleverly done. The adventure could still be as enthralling as any of the other movies, because the adventure didn't just come from Indy outrunning things. It came from story, plot and exotic locations and mystery.
Wearing the same outfit wasn't the problem. In CS it was too pristine. I wouldn't mind seeing an older Indy that gets scruffier in the field as time goes on. He should have been more scruffed up in CS. It would have been more suitable. It wold have created a greater contrast between his professorial self and his adventuring self. Indy5 can fix this.
He needs to shoot someone, as base as that sounds. They have to put more balls back into his character, but with all the current political climate of gun issues that might be tricky.
There was a time when I thought you couldn't have an Indy who didn't run full pelt and perform to the level of the trilogy, but I wouldn't mind seeing an adventure that had at least some element of intellect, possibly contained in the mystery part of the plot.
Amongst other things not said, I do keep this in perspective and realise it is just the wishes of a fan who has been spoiled by Raiders and could keep watching IJ do his stuff as both he and I get older. What I want may not be what the general public wants, but I think there are still good legs in Harry's Indiana Jones.