What is rome's destiny as foretold in the aeneid? what stands in the way of success?

In the Aeneid, Rome's destiny is to be the head of an Empire that rules over the entire known world.

Aeneid is a Trojan who flees to Italy after the fall of Troy. He is destined to be the founder of Rome and of the lineage that rules it, but the goddess Juno hates him because he is Trojan, so she tries to stop him from getting to Latinus, and when he is there she unleash war over him and his followers.