The most recent three films in the Indiana Jones franchise have had perfect endings that could (and should) act as the closing moment of the series. But when there’s money to be made, there is sequel potential, no matter how many years pass in between.
I think, even though the film itself has been divisive, they could have done a lot worse than Indiana Jones and the Dial of Destiny, the franchise’s fifth entry, which has finally been released after years spent languishing in development hell (fifteen years after the last Indy adventure, Kingdom of the Crystal Skull). Dial of Destiny largely plays it safe, without explicit willingness to take risks, which does remove some of its efficacy — you might expect a legacy sequel in one of the more consistent long-running franchises to diversify itself in some unique ways, but Dial of Destiny sticks relatively closely to the script that has made the series successful for decades. I can’t fault it; after all, why mess with a winning formula?