@ArdainianRight @xianc78 Well, I think in that case, China would take advantage of that and expand their Silk Road project at a faster rate. Probably, they will try step in and replace any USA aid to Africa and Middle East by their "Yan Swaps" thereby taking indirect control of African and Middle East economies, only to force them to cooperate in their Silk Road project. Secondly, I think they would try to co-opt any market damaged by the fall of America ( from Silicon Valley all the way down to gas and oil industries ). Third, they would try to position military any of their allies ( Iran, India, China, Brasil, Venezuela, Russia, etc) in the geopolitical chessboard.
I do think an expanded war in the Middle East could easily lead to pressures that break up the US. The social fabrics that once motivated young men to give their lives in the military are gone, and any attempts at conscription could easily spark revolt. It's one thing to go along with a fake and gay regime because you're too lazy and comfortable, it's quite another when you're forced into action. Vietnam draft backlash tore the nation apart when it was far more socially cohesive, and the population was far fitter.
But really, the US government is far more of a load-bearing pillar for the global order than many realize. Even an internal crisis that falls far short of total war or total collapse could have massive ramifications. What happens if foreign aid to Africa and the Middle East dry up? I'm not even convinced we'll have an organized "World War 3" with discrete power blocs, more like a wave of regional wars due to the power vacuum caused by an America rendered impotent by internal divisions and economic turmoil. All semi-advanced nations are too old and decadent to really be able to stomach the kind of total war mobilization that occurred in the World Wars.