These characters are all fan favorites and requested, so they will add them eventually but I dont know when
Except atticus, the others will never come out
It is hard to know. They may simply create some characters to keep on hand without a necessary plan for an event to add them to the game. I don't know how much they listen to the surveys. Seems like they mostly add characters they believe can follow the plot of events better. And now it is even less of a chance for requested characters with how they only added 3 to dsod world to purposely have less newer ones overall so that unlock events for months will be filled for Yugi, Joey, and Tea instead of just adding them to the new world so that we have more open slots for characters we don't have yet in other series or who weren't leaked for dsod. It is all about trying to give less overall gems since they realized how much a new player can get from a new account now with the new worlds starting to pile up.