I wouldn't mind seeing Ford give it one more go, but I wouldn't mind a James Bond-style recasting either. After all, the character was somewhat inspired by Bond, and they got Sean Connery to play his father. And as noted above, Indy has already been played by, chronologically by age, Corey Carrier, River Phoenix, Sean Patrick Flanery, Harrison Ford, and George Hall. And apparently an uncredited Andrew Simms as "Young Indiana Jones" in Crystal Skull, according to IMDb, but I don't remember where that was in the film. And that's not counting the people who played him as a baby or did his voice in video games.
Besides, due to the gap between feature films, the chronology skipped over the entirety of WWII and most of the '50s, so recasting Indy with an actor in his 40s (since Indy was born July 1, 1899) would be the only way we'd get to see that missing era.