So this is my logic to what would happen to 40k if the emperor died.

If the empower died the Necrons would be able to destroy the warp and end life to all races with souls. The only races that would be left are the Necrons and the tau. The tau and the Necrons would be in a ever lasting war. Also this is a bit off topic but i think that the guys in the uk made the seem like north Korea(Witch is what I think they were thinking about). The reason that I am saying this is because you have a caste system. The tau is true communists. Also they go get tattooed and go to fight. But now back the empire, some may argue that orks don’t have should but they do the space merains just don’t think so. Also eldar believe that they don’t have souls but they do. I want to know what you guys think about what you logic is and who do you think would win the Necrons or the tau.