The first Indiana Jones movie, Raiders of the Lost Ark, was released in 1981 and set in 1936. Releasing a movie now with the same time difference would mean it's set in 1981.
@estherschindler Who would they use for the 1981 bad guys? The Soviets? They just were not as colorful as 1930's Nazis. The post-Mao, proto-corporate Chinese? The inept North Koreans. No, Indiana Jones needed the Nazis.