I do think that here in the U.S. we should suppose clay tennis more. Why the US has such a dislike for clay now I will never know. We used to have more clay court Tournaments. But now they are almost 100% gone! And yet then when a clay court Tournament is in full swing in Europe or elsewhere some Americans stupidly wonder why Americans can't play on clay
Also without a lot of strong top tennis players in the U.S. tennis has lost a lot of popularity in the U.S.
I had the impression that there were more claycourt futures in the US now, especially in Florida near Bollettieri's academy (edit : I see someone had said it before
I also had the impression that there were still a few players from other countries improving their game in such academies, as Nishikori did.
I don't have the impression that European academies have developed that much (although Taro Daniel spent most of his time in Spanish futures then I guess he practises in Spain).