Yeah, because as far as I know we don't have a 3D model for him rotting away in some digital folder, I don't think it'd happen some day soon, but maybe. Maybe even some other Ailing Kingdom-themed cultists, too.
It's intended that Gunners and Assassins are a fair bit rarer and harder to achieve than the three main classes, but over time we will add more ways to get Gunner and Assassins, like what we have with the Christmas Soul.