I think all great characters are just that -- characters. And while I love Harrison Ford's performance as Indy, I think there is plenty of stories for Indy to tell, and unfortunately Ford is not getting any younger.
I'm not too keen about watching a 70+ Indy with his biker son off on some quest during the Age of Aquarius, fighting drugged-up hippies and the Vietcong.
Before we get there, I say turn back the clock and have a great young actor revisit the Young Indiana Jones Chronicles for the big screen. Harrison Ford can narrate as the older Indy, similar to how they did it in the TV series.
The 20s and 30s are just such a cool era and there's so much possibility as long as they manage to liberate Indy from the constraints of Lucas and Spielberg's narrow formula. I was discussing this on another forum so will just add here what I said there on the subject:
I really believe Lucas and Spielberg do themselves, and Indy, a disservice by keeping the films locked in this tiresome formula, i.e., racing against the bad guys to find a McGuffin with supernatural power, which, if fallen into the wrong hands, could plunge the world into darkness. It worked great in Raiders. Was different enough to make ToD enjoyable and fresh, made LC look like retread, and more so with CS.
By insisting on this formula the franchise is destined to fade and die. The only way Indy can survive in a long franchise, in my humble opinion, is to free him from the chains of these conventions, which is what Lucas actually did with the Young Indiana Jones series.
I would love to see a reboot of a big-screen Young Indiana Jones franchise that takes him on global adventures and out of the tiresome mold of simply chasing after a McGuffin before the Nazis, Commies, Thuggees, MPAA or whatever, get their hands on it.
It'll be interesting to see whether Indiana Jones really does survive Lucas and Spielberg, but seeing the amount of passion, and the many, many fan films that are out there, I'm sure he will.