Although the United States seems to prefer other sports, much of the world loves, and will continue to love futbol. Conflicts have been solved over this game, friends made, and countries brought together. It is such a nationalistic sport, and I do not see it's popularity decreasing anytime in the near future.
Futbol has brought the world of sports enthusiasts together. The popularity of the World Cup shows global adoption of this sport. Futbol is a sport that can be enjoyed by both men and women and requires minimum equipment for children to play. As safety concerns over full contact sports such as American Football increase, more parents will encourage their children to play futbol/soccer.
As seen in Fifa World cup 2014, people booked tickets 2 3 days early from the match. There are 1 Billion+ Viewers of Football around the world and I don't think so that football can decrease in popularity. Fifa World Cup is the tournament that is mostly seen by the People all over the world.
I do not see any decrease at all within the Futbol community. Almost every coutry in the world cherishes it as their main sport. I hear two new arenas are being built for the World Cups that occur within the next eight years. As they say in Mexico, "Viva futbol!"