Let's consider why ICAO standards were promulgated in the first place. To ensure some kind of standards in pilot training,one assumes. Once a pilot attains an ICAO licence, it should be recognized by all signatory countries' authorities. Seems simple enough.
As for the US, many airlines send their cadets for training there because a fine weather training area is easy to find, and costs are much lower than in the EU,as stated elsewhere.
Lufthansa has been training such cadets as their source of pilots for years. Quite successfully too, it would appear.
Because of these factors, some American Universities and FTO's tailored courses to train JAR cadets, but these fell by the wayside during the economic downturn. Now, they will have to retool to train to EASA standards.Can we expect training to return to Europe with its weather and expense considerations? Don't bet on that.