Hotel prices and airfare have been rising by leaps and bounds over the last couple of years in anticipation of this event and the Olympics. Rio is considered to have a shortage of hotel rooms and is now consequently seen as one of the most expensive places in the world. Prices may come down slightly after the Cup (as they do after Reveillon and Carnaval when they are jacked up 3-5X) but I doubt there'll be a significant decrease until well after the Olympics.