People often overlook the fact that the SH is trying to help the NH with their rugby. The Tongan Thor is a mercenary. He got told by the All Blacks that he wasn't ready yet and so he took off to Aus. He wanted the big bucks straight away and fair enough I guess. If the US really took to rugby, they would be as you say - rapidly developing. They'd be a force in no time and would probably rise over some of the tier one nations that have been playing longer.