You apparently never learned about the 1939 New York World's Fair's "The World of Tomorrow" expo. That didn't wait for the century half way point. How about the 1900 Paris Expo and the 1933 Chicago World's Fair, which both also featured predictions and prototypes of future technologies that got everyone from workers to sci-fi writers focused on flying cars and moving sidewalks.
Hardly anyone on this site has any sense of history and people just make shit up about the past. How sad to see a once intellectual forum turn into another Reddit or Twitter.