Maybe I'm mis-understanding the OP, but I feel like I read/hear this narrative pretty regularly, whether it's for soccer or every 4 years during the Olympics and some Americans start wondering why they're not crushing it at <insert random sport, likely handball, here>. I get the underlying point, that there's so much unexplored talent that could be put to better use in the US than being the Xth-better player in basketball/football, but it still seems like such a uniquely American framing of the issue, the sports equivalent of neo-cons thinking force will solve any foreign policy problem.

Since we're talking about soccer here, for a lot of the countries seen at the WC, that is THE major sporting event, uniting the whole nation in a way nothing does in the US, by any extent. In a lot of cases the lack of population has been overcome by the passion, dedication and organization to figure out a system that can provide the most success at that stage (see: Uruguay, Iceland...). Not saying any of that cannot be replicated on a smaller scale in America, but even if the current lackluster efforts of US Soccer are overcome, there's still something to be said for having a grassroots culture of the game. It exists on fields all over the country, but the vastness of it makes it a very big challenge to coalesce into something coherent. Maybe the MLS is the right solution to that (if US Soccer figures out the minor leagues thing), maybe not, but IMO the culture is still ages away from existing organically, and that is the toughest thing to replicate and sustain.