Hickman's story arc: The Beyonders shutting down the multiverse simulation they are running by terminating the defragmenter (Galactus) and initiating the kill switch (molecule man) in each of their multiversal simulations is what I want to see as the big threat in Avengers 6.
That could even fit into why Thanos wants to destroy earth and half the universe, to restore balance, prevent the impending multiversal collapse with earth as the point of collison and so that the simulation takes up far fewer resources so that perhaps the Beyonders could continue running it.
Basically the next phase should cover and build up to Jonathan Hickman entire run at Marvel.