Some would say that the war is being fought as we speak, economically.
War is never imminent - it is decided by countries and politicians when it suits their needs.
Historically, China has seldom sought to expand past its borders even when it had the means to do so (during Marco Polo's visit, the Chinese navy was larger than the combined navies of Europe!).
The Chinese prefer to conquer through economics and bribery. Throughout history, it has sought to open up trade and accept vassals (by giving gifts) instead of outright occupation. In any event, I believe that the Chinese are very pragmatic people - and the long and short of it are that they wish to be left alone to make money.
However, there are 2 things that may put the US and China on a collision course:
1) The touchy subject of Taiwan. View it this way: During the US civil war, if the Southern army instead of surrendering to the North had instead escaped to Hawaii and then built up a different country there, would the US now use all means to recapture the territory? If Hawaii then had the backing of the former Russia, would it change anything? If Hawaii then declared independence, would the US allow this to take place without taking any action at all? My view is that if this situation is treated sensibly, and a face saving structure is put in place, this can be sorted out without any resort to war.
2) The question of Japan and its war time role in Asia, for which it has never apologised (read about the Nanjing massacre - in which the Japanese had killed anywhere up to 600,000 Chinese civilians in a few weeks).
Again, think of it this way: If the Germans after WWII had not apologized for the holocaust, and its prime minister today still visits the grave of those who perpetuated the extermination of the Jews (the tomb of the unknown soldier in japan contains the grave of Japanese war criminals), their school books still claim that Germany was not the aggressor in WWII, forced Jewish women into sexual slavery, tested chemical weapons on civilians (BTW, the perpetrators were never convicted in exchange for giving their research to the US military) denies the Holocaust took place, and at the same time, Germany wanted a permanent seat on the United Nations, would the Jewish people agree?
China has been stepped on by many countries in the past (see opium wars, the Japanese invasion during WWII, the foreign zones in Shanghai shared by the western powers etc)
and now has the economic power and military might to stand up for itself.
To solve all the historical baggage without incident, we have to be sensitive to all that has happened in the past so that it is not repeated. If we make intelligent policies taking into account all the historical factors, no one has to go to war.