Hmmmm, how about a longer WW2? The Americans don't intervene, and the war is won by the British and Soviets alone. The Soviets, who liberate much of mainland Europe, integrate all of mainland Europe into the Warsaw Pact. Britain then has a massive Labour victory, and they join this new bloc as a trading partner. The Americans unify the Caribbean, Canada and Mexico into their sphere, maybe annexing Cuba and making Puerto Rico and the Phillipines into states. The East... maybe the USA stays isolationist for too long, and negotiates a peace with the Japanese, who continue the East Asian Co-Prosperity Sphere? Then African nations, led by a non-apartheid South Africa, Halie Selassie in Ethiopia (maybe the Ethiopians threw off the Italians by themselves and now have mad respect?), socialist Ghana and Nasser's Egypt, create the AU much earlier, and make it stronger. South America ends up under an extended developmentalist trading bloc, led by Chile and Argentina.