Free Market societies usually prevail, and rise to the top. Free Market sports will probably do the same. For years people have been beating the drum that the pay to play system is going to fail, and the US teams are going to crash and burn. Yet here we are, still watching thier success, and watching duel national players (who were raised and trained in the US) play on other National teams.
I presume you're talking about the girls side re: dual national players training here. I think that has more to do with what @kickingandscreaming brought up about the US being amenable to girls soccer earlier on than other countries. You will see more and more women wanting to play for the girls sides in EPL and La Liga, especially when it becomes clear that coaching in the US is inferior. Like I said, give it 10 years and the USWNT will be struggling (of course, unless something changes here).