Dunno, if he wanted, he'd make more videos, and maybe with a story of them. Darkiplier was just a reoccuring joke before it got too popular. Dr. Iplier has a lot of Nicaragua-related story. Others are just one-time characters that were made of live action videos. (I don't know when and why they started to be called Alter Egos, it's technically incorrect)

yes I agree well fans and also Mark calls them his alter egos. Anyway, everyone of them gives us a refreshing mood to keep us entertained and not get bored with the same content over and over. Maybe Darkiplier will only occur during Holloween.