The main point of Animal Farm is that revolutions, no matter how idealistic they may seem at their beginnings, always lose their purity. They stop being useful to the people whom they were supposed to help. Instead, they get to the point where the leaders of the revolution look no different than the people who ruled the society before the revolution. We can see this quite clearly in the last line of the book. The narrator tells us that
The creatures outside looked from pig to man, and from man to pig, and from pig to man again; but already it was impossible to say which was which.
If Animal Farm is prophetic, then, it would be because revolutions in the years since 1946 have followed this trend. In general, it is safe to say that they have. We can look at the revolutions in Cuba and North Korea, for example. In each of these examples, it is very hard to argue that the people of the countries are better off than they were before the revolution. It is also easy to see that the leaders of those countries have come to be like the pigs of the book. They tend to have much better standards of living than the people with whom they are supposedly equal. This is without even mentioning China which is still nominally communist but seems capitalist in almost every way.
Thus, we can say that Animal Farm has been prophetic. In 1946, there was still some hope in some people’s minds that communist revolutions might change the world for the better. It has become clear today that Orwell was right. The communist revolutions essentially just led to situations where the communist leaders today are no better than those they supplanted.