Problem is the USA already follow three other major sports- NFL , baseball and basketball. I read that baseball is on the decline though, so maybe soccer could fill that void eventually. For me, all the play acting 'injuries' and low scores a put off. Granted the excitement in the audience is incredible when someone finally stops clutching his knee, gets up off the ground and scores.
For Americans, rugby SHOULD be of more interest than soccer.
Me, I'm an Australian, so we already have the best team sport in the world- Aussie Rules 🙂