It's a matter of degree. Muslims in the US on the whole tend to assimilate. Those in Europe do not tend to do so. It's a fortuitous byproduct of our immigrant history, not that it's ever been smooth here for new immigrant groups.

That being said, there have already been enclaves of US Jihadists prosecuted and there'll be more.

The only way I see Achmed the Average Muslim in significant #s being persecuted here would be if there were a large successful terrorist attack, such as a dirty bomb or bioterror killing beau coup folks. The aftermath would likely be extreme vigilantiism, just what Osama would like to see. The start of a real religious war.