Things seem to move more slowly in Fantasy,
but if l had to take a guess
1. Chaos claims the whole world with a unstoppable army.
2. Empire / HE / Dwarfs combine forces and find a way to close the the gateway and banish chaos forever from there world a slowly deal with the other races such as VC, DE Ect.
3. VC mass turn humans in to vampires and claim the world.
4. Skaven mutate in to a race of super creatures that take over the world.