Dr.Sartorius said:They're waiting till Ford is pushing 80. Why couldn't Spielberg make Indy 5 before these two other movies? Age obviously isn't an issue because they're just going to reboot or have a sidekick replace him for Indy 6.
That's more Disney's doing than Spielberg. They have their big franchises to deal with in the coming years including Star Wars and the Marvel movies. Both this year and next year are slammed with big studio tentpole flicks. Having Indy 5 as a late summer 2019 is probably its best chance for the movie to make money. It will also give them time to do all their marketing and theme park tie-ins.