Simple question really: What if the Avars don't migrate west? A possible POD could be that the Gokturks never rebel against the Rouran, although I don't think it is known for sure if the Rouran were the ancestors of the Avars. Please correct me if I'm wrong.
Anyways, if there are no Avars, what happens? The Byzantines will certainly have an easier time, since the Slavs will probably stay north of the Danube ITL with no Avars to force them west. What do the Lombards do? What happens to the rest of Europe?