As far as the stories go, I personally wouldn't be interested in reading material that added to the story by well-meaning fans. I want to know what Comicality had in store for those characters, in his own brilliant mind. Of course that's just me. I'm sure other readers will feel different.
You're absolutely right, I would love to know what Justin's fate was. You couldn't help but fall in love with his characters. They'll outlive us all, if we don't blow ourselves up. New people, perhaps people not even born yet, will be finding Comicality's stories in decades to come.