Speaking very generally, the first and biggest hurdle is cultural. Football, baseball and basketball are the first three sports in this country, by a wide margin. Less than an hour and a half after this match is over and I can't find a show on TV running a program on soccer, the US match or the WC in general. In a country like Argentina, there is soccer conversation going 24/7 on some major outlet.
Most of our youth are given a football, basketball or baseball and told to go outside and play. Most of our kids aren't out in the street kicking around a soccer ball or at the park playing pick-up soccer. As mentioned earlier, that is necessary to develop instincts, touch, feel for the game, and to explore how to play with a ball at your feet. Most other countries you'll see the majority of kids playing soccer. So, those kids are already developing a lot of skills before they even start organized training.
Youth soccer in this country needs to be free to play. That's the easiest, fastest way to attract large numbers into the sport. Then, they need to receive actual technical training, not the BS too many get which is to throw out the best/fastest athletes and play chase. Someone mentioned it earlier, get rid of the win/loss component at those early ages and focus exclusively on skill development. We need coaches who can and will do that. The technical abilities between US and other countries is a monster gap currently
Professional levels in this country suck in comparison to other countries. Biggest hurdle, and it isn't changing any time soon, is lack of promotion/relegation. MLS isn't going to move to that so that's a major block. Without pro/rel, and the incentive that creates, the US will remain a soccer satellite country indefinitely. We are able to athlete our way to a 15-20 global ranking but that's the plateau under our current systems.
People think I'm an idiot or something, because all I do is cut lawns for a living.