What if after defeat in successive battles against Arabs in Syria, the Byzantines decided that instead of defending Anatolia it was better to move to North Africa and shift capital to Carthage. Defend Egypt and focus on an empire based in North Africa. That would be easier to defend, easier to get support from European powers and not get isolated in Turkey for centuries to eventually lose. At max they could have lost Egypt but would have held on westwards from Libya onwards and with local support of Berbers. Would this have been a better strategy for survival.