After some binge reading through some no-Islam/no-Arab conquest threads on this forum, I have noticed that there seems to be a consensus that even if Islam never happened that the Arab Conquest would have still happened thanks to a myriad of reasons.
This made me wonder, with a point of departure from the death of Justinian in 565, is there any feasable way for the Romans to hold onto their core land of c. 600 A.D? Would there be any feasable method the Romans could have used to repel the Arabs, like for example using them against the Persians? Would butterflying a bad emperor, religious controversy or war result in an empire strong enough to hold onto their power?