I was reading my daily excerpt from the History of Ideas, and I ran into this quote:
The destruction of Carthage robbed Rome of its great fear, and this led to a moral relaxation. The Roman conquests had become too vast -- her empire was beginning to break under its own weight.
This reminded me of the sports psychology commentary regarding the 1998 Sammy Sosa / Mark McGwire homerun slugfest. Roger Maris' record had stood for awhile (~30 years) and they both blew through it. There may have been other factors (begin ticking off any number of MLB complaints ;), however having an equal to fight against provides great motivation.
So, does the US need a competitor? And on what bases will the US compete? I'd love to say the US has gone Post-Imperial. However, I think that's premature....