The re-consolidation of the global power distribution into a bi-polar configuration was highly probable. After 1945, the world was dominated by two nations, the United States and the Soviet Union. There are numerous reasons why it was extremely probable.
First, the human losses of the World War II (1939-1945) were enormous. The total number of deaths was somewhere between 35,000,000 and 60,000,000. The loss of so many people in such a short period of time was unprecedented. Germany lost a large percentage of its men. Although the Soviet Union lost many millions, it still had ample manpower for its large armies. America suffered relatively few casualties.
Second, material and economic losses were huge. For example, Britain, on the winning side of the war, found itself in debt afterwards. Its financial problems ensured that it would no longer be a great world power. Other nations, such as Japan, China, and Germany lay in ruins. America emerged from the war as a rich and thriving nation. Its cities were not damaged. America's infrastructure was intact. Also, in spite of severe damage, the USSR was still able to produce munitions and nuclear weapons.
Great Britain, France, Germany, and Japan had been great powers before the war. However, their human and economic losses prevented them from playing a big role in the post-war world.
France tried to maintain its great power status after the war. This was a daunting task as the nation had been defeated and occupied by the Germans. Its economy grew rapidly after the war. But France weakened itself by trying to hold on to its empire. It suffered humiliating defeats in both Vietnam and Algeria.
The United States and Soviet Union had not been on good terms before the war. But their wartime alliance brought them victory in WWII. The elimination of the Axis threat posed by Germany and Japan meant that they no longer had a common goal. Therefore, a return to the status quo antebellum was not surprising. Also, after the war, the two countries stood for contrasting ideologies: capitalism and communism.
Finally, American and the USSR were the only two countries capable of producing large nuclear arsenals after the war.