If Indiana Jones would be played by any other actor I wouldn't give a credit of trust to Indy V. But Harrison Ford is the only man, who could make it work.
Indy V will probably be less depended on action scenes (or the fights will be done younger side-kick or even younger version of Indy). But the question I ask myself is: if the main hero will be more "thinking character" this time, will the fifth part be as good as the previous ones?
One of the key elements of the Indy movies is the dynamic action scenes with the main hero in the center of all the trouble. I am very curious how they will resolve that.