Sounds like you have sold it to yourselfWith regard to war: There has been a major paradigm shift during the latter half of the 20th century that drastically lessens any risk of all out war between two major economies. Firstly, we still have the concept of mutually assured destruction that prevented the cold war escalating to WWIII and additionally we have seen the occurrence of globalisation. Despite what the hippies might say, globalisation is one of the largest factors contributing towards world peace: major economies are so intertwined that war in very unlikely, previously there was money to be made in warfare, now the risk to trade is so great that both nations would suffer. The U.S will never go to war with China or Russia without another huge paradigm shift.
People thought along the same lines in the booming 20's. Little did they know the most distructive military conflict in history was less than a decade away. It only takes one person with a vision being followed and a few deals with the right leaders for us to be tangled in world war III.
The US is already involved in proxy wars against China and Russia.