Kate Capshaw talked to People Magazine about a new Indiana Jones and here's a bit of the interview
People : Is Steven doing another Indiana Jones?
KC : Yes, sometime next year. I believe Willie Scott's going to be making an appearance too.
People : What will that entail?
KC : I can't say. Not because Steven's sworn me to secrery, but because I really don't know yet. All I know is Willie might be coming back, Karen Allen, and possibly Calista [Flockhart]. I think Harrison's going to be outweighed by the women in the next one.