My prevision / wish list :
when there will be a chaos demons focus, they will be used like chaos beasts and maybe then as a warband (would be more interested as NPCs from fluff perpective)
when there will be a Death focus
Zombie doggos, bats and the likes will be used as chaos beasts
as a twist, when a model dies, replace it with a valid Death model costing the same points (this could be easily home brewed)