Doing a little re-reading of the Short History of Byzantium and re-read the Justinian chapters. So it occurred to me, what if for some reason Justinian felt that recapturing Italy was a little too much for him to chew on and instead settled for Africa (and maybe Sicily which I gather was easily regained)?
He has more resources, manpower and money directed at the Persians or strengthening the rest of the empire. What effect would the plague have on a slightly more populous but smaller Byzantine Empire?