It's interesting you should say that, cause I think I've been hearing that the US players are now being trained more like the clay courters, except maybe on HC's so it's not working out the same way, so that's why the young talent isn't as strong now as it once was.
Even if what you said is true, I have a hard time seeing it being implemented. It is hard to diverge from what has been taught for generations. To me, the biggest problem facing American players is the lack of adaptability. American hardcourt tennis is tailored to fast surface and the courts are not what they used to be. The slowing down of the court benefits those with patience and good defense which are easier to develop on clay. IMO, the best way to help American players is to speed up court which I doubt will happen anytime soon.