The ship taking Convolvulus to Rome never made it.Convolvulus' discord-sowing went horribly right, and in the ensuing chaos the ship was either damaged or caught in a storm, and went down with all hands, including Convolvulus.
Dubbelosix's specialty was a life-prolongation/eternal youth potion.Unfortunately, it only works on houseflies.
The brew they drink regularly for strength in battle may have basis in truth.
Getafix secretly wants the Gauls to be part of Roman EmpireNote also that both Gauls and the Romans use the normal font, and Asterix and Obelix never have any problems with understanding Romans. They speak Latin. It reaches its peak when they outright admit in the Olympic Games that they're Romans. They benefit from a lot of Roman infrastructure (roads, bridges, entertainment). Many Gauls claim that Ceasar is actually the greatest leader of their age - see the Laurel Wreath for instance. The only reason why Getafix uses the magic potion is to keep Cesar in check.
Astérix and Son was going to be the series finale.You can't get any more closure than Caesar and the Gauls sharing the banquet.
The finale will be Astérix and the Ides of March.Getafix is the soothsayer.