I have let my friends know that I don’t believe soccer will be an important American sport beyond the high school level.
My reason is that soccer appeals to people who live in societies with an hereditary upper class ( most of the world). Soccer is based on each person playing a wide variety of athletic roles ( excluding the goalie) for the entire game. That type of game supports heroes and athletes with a broad skill range. It is conceptually anti-meritocratic.
The primary American sports of baseball and football are based on specialized skills. America is one of the few societies without a hereditary upper class, that is entirely meritocratic. Therefore our sports are conceptually meritocratic.
Football, which became popular after the end of our hereditary upper class (1959) has separated defensive skills from offensive; it has separated most of the positions on the field into specialized athletic functions. Baseball allows substitute batterers, runners and has a constant flow of pitchers.
Baseball and football because they have very specialized athletic functions reward meritocracy and are therefore very American.