In the papal conclave in October 1978 following the death of Pope John Paul I, Cardinal Benelli, Archbishop of Florence, came within 9 votes of being elected. But he died in October 1982.
He had quite big impact on evolution of anti-communist movement in Poland, and since successful activities 'Solidarity' were important to late 80s fall of communism in whole Eastern Block, we might see some significant butterflies.
However here comes the question , often if we remove an important player from a universe , a replacement is found of equal importance because the necessity exists. The problem is that few people in this world are as popular or have the influence as the Pope. And a Polish Pope at that.
Maybe the butterflies are fewer than we believe because the Americans find some other way to evolve the anti-communist movements to the rate in which we would have the dissolve of the Soviet Union by the time we got it ?
A world without Pope John Paul II? That would be a sad world, the image of Catholicism was changed by him, showing that all people are Gods children. Also, lots of religious dialogue was started by him. Truly a great man