I agreed with all of your post, except for this.
I don't think this is true. Lebron James or JJ Watt can't decide at age 15 they want to be soccer players, and then soccer in the USA will improve. You wouldn't have ever heard of them if they did that. They wouldn't be good enough, and they would've never made it as pros.
This is 75% a problem of not enough kids who grow up their whole life dreaming of being footballers, starting when they are 2 or 3, playing all day from the second they get home from school to the second they go to sleep, along with knowing that they have to make it as soccer players, they can't fall back on saying they can go to Stanford and become a business executive making 500K per year. In almost all the countries that are producing the top players, this is the formula they follow. If a kid from Argentina or Colombia doesn't make it as a professional footballer, he's probably not going to have a very big paycheck. You either have the kids with that desire or you don't. You can't teach that, Pulisic had it, there will need to be more like that. And its 25% of a problem with how poorly organized player production is in the USA, which is definitely getting better, but is still a complete mess compared to the top countries. That'll take some more time.