Final answer:
Winston Churchill is predicting the outbreak of World War II.
Step-by-step explanation:
The future event Winston Churchill is predicting in the passage is B. The outbreak of World War II.
In his speech, Churchill is referring to the growing division between democratic and Communist nations in Europe. He uses the term 'iron curtain' to describe the barrier separating Eastern and Western Europe. This prediction foreshadows the outbreak of World War II, which was sparked by the increasing tensions between these two ideological camps.