This is a bit I've been thinking about a lot, and I am not the first nor will be the last to pontificate on it given the unending sermons former USMNT players have given since our rank exit from the World Cup, but I do believe there is a fundamental cultural hurdle that won't be solved even if we were to copy Spain's or France's developmental philosophies page for page tomorrow morning.
American families and children love optionality in athletics. Even with all the moaning and groaning of "early specialization", travel sports, pay for play, so on and so on and so on, we are still fundamentally a culture that values kids playing multiple sports at a fairly high level until they are at least 10 and most likely 13 - 14 years old and often times even later than that. I tend to think that is a better, more holistic view of athletic development than hyper-specialization at a very young age for the vast majority of kids, and it appears the majority of American families think the same.
Where the Spains and Argentinas and Frances of the world differ and why they are so good at this is that their versions of being a multi-sport athlete are 1) playing at the top level of soccer, 2) playing at the second level of soccer, 3) playing at the third level of soccer, 4) maybe basketball or tennis, 5) maybe rugby, 6) playing at the fourth level of soccer, 7) the next levels of soccer... The La Masia's of the world down-select kids in middle school and effectively tell everyone but about 400 13 year olds that they aren't good enough to continue to play this game beyond the age at which they are. Americans would never, ever go for that.
I'll give a quick example that I am running into right now: my oldest (6 years old) was on a travel / all-star baseball team (I know, I know) this spring with a bunch of kids from his town / school district. The very best player on his team was an absolute stud athlete who is a very late birthday (June), so he didn't turn 6 until the season was nearly over. Nevertheless, he was the best player on the team by the end of the year, loves baseball, so on and so on. Did I mention that he was also playing in our USL-affiliated travel soccer league (a year up - he was playing U7 soccer but U6 baseball while he was 5 years old) and his mom was a high level D1 player for one of the better soccer programs in the country? Also, his dad was a borderline D1 basketball player as well, and the kid loves hoops. If that kid had grown up in Buenos Aires or Madrid or Berlin, he would have only had a soccer ball at his foot from the time he was 2 years old. Instead, he (rightfully) wants to play everything and enjoy life and sport until he is in his teens because he is good at everything.
It is a fundamental cultural disconnect that I think wouldn't be solved with a genuine restructuring to mimic Spain, England, France, the Netherlands, what have you. I'd be interested to hear ideas on how to innovate to get around it.