According the Varg, the slaying of Euronymous was in self-defense. I always get angry with those who bad mouth him for killing when all they know is that Varg killed someone.
I doubt that Varg will do anything bad outside of prison. He will probably write some books, hopefully make another Burzum album, just be productive.
I just hope that no one tries to kill him. People are extreme, so I hope that he stays safe.