How does the author use foreshadowing in The Road to Memphis?

Over the course of the novel, segregation shows itself to be impossible to maintain, as the young blacks grumble about their treatment, foreshadowing the advances in civil rights to come. The group's generation is about to fight World War II, during which time the US military will insist on equal treatment of all soldiers. Once the war is over, and the surviving soldiers return home, equal treatment under the law will become a national movement by the late 1950s. In the 1960s, attempts will be made to integrate schools and workplaces. Segregation might still happen, but it will not be required. It will also not be supported by the law.