That is all true. However I would say that the divisions within US society (black vs. white, guns vs. no guns, abortion vs no abortion, tax rich vs. tax no one,

That is all true. However I would say that the divisions within US society (black vs. white, guns vs. no guns, abortion vs no abortion, tax rich vs. tax no one,...) and the horrible public education system will be its biggest challenge going forward. At the end of the day, empires are build on economic / technological advantage - Roman army & aqueducts, British longbow, French knights, British steampower, US microprocessors,...