That's the problem with fighting the Norsca and Chaos in general. It is a ceaseless tide ready to bury the world. I can't imagine the time that goes into making these man, spectacular job
If you have 2part cinematic you can do like... - The Empire or Bretonia or Dwarf near lost Beastmen in part 1 but they have unexpect alliance like Wood Elves come to help them in part 2 - Because 1. Wood elves hate Beastmen more than human or dwarf 2. Wood elves want Bretonia or The Empire come to be shield Athel Loren from other enemy Tip - Karl Franz is the first emperor of Empire who go to Athel Loren and made alluance with wood elves to deal Horde of Beastmen
Sometime when The Empire near lost by Skaven or Chaos - Vampire Counts come to help them in last minute - Because Vampire Counts want to rule over human - some vampire manipulate Empire in shadow - but Skaven and Chaos want to destroy without left anything to vampire - Vampire don't want like that - They come to help in last minute because if they come too early . It end to fight with human before