One reason I don’t see soccer becoming important in our American future is that soccer players help each other get up, both sides. Very un-American, it never happens in professional sports.
Starting now we will be getting TV instant replays for critical decisions in tennis, and soon after tennis we will be getting instant replays for basketball, just as we now have it in football. Which brings to mind the fact that tennis, basketball and football all have multiple referees on the court or the field. Soccer only has one decisive referee in the game.
Hypothesis: Americans are much more concerned about winning and the rules for winning than the rest of the world. Sports and games are a simulacrum of society. Americans may be more focused on winning by merit and less winning by chance.