Mare Nostrum

Marcus Aurelius adopts a suitable general and makes him the Emperor.As such,the Emperor of Rome after Aurelius dies is NOT Commudus but this general.This general has a much better term as Emperor than Commodus.As a result,Rome lasts longer and when it collapses,it is split and reunited several times.In the modern day,Rome is under a single Emperor.What if this had happened what if the Mediterranean remained the Mare Nostrum?