Reuniting the Empire

Could the Roman Empire realistically ever have reunited following the collapse of its Western half up to and including 476? The Byzantines had a go at it, but as we know it ended up costing them dearly. Is there any chance that they could have had lasting success in recreating a mediterranean empire? Could anything have made the Byzantines merge with the Carolingian empire (although they [the Byzantines] where hardly big fans of the Carolingians from memory), maybe in the form of a personal union? I know that the Carolingians weren't exactly direct decendants of Rome, but atleast it would be a pan-european Empire. "Lasting" here would for me be half a century or longer.
 
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