He'll be killed by one of the dragons most likely.
i could see victarion having a change of heart and deciding to back dany in her bid for westeros in return for control over the iron islands
of course one flaw to this is that a lot of the men with him are probably loyal to euron
also victarion doesnt seem like the kind of guy that would use this method to take a throne
gotta pay the iron price, and getting a chick with a dragon to beat his brother might not be considered this
either way, i dont think he rides a dragon