This seems like the most likely thing to happen, IMO. Bolvar already has been Lich King for awhile and the Death Knights seem loyal to him. I could see him taking up the mantle again to make sure the Scourge are calmed down again. I canāt really see Bolvar going back to ānormalā life easily, for that matter.
Itās also hard for me to see Arthas being redeemed, let alone him becoming a āgoodā Lich King again, and in my opinion, he shouldnāt be redeemed. Iād be surprised if he wasnāt just drop kicked into the Maw again at some point. I also canāt see the Death Knights wanting to follow him again, given the majority of them are what they are against their will because of him.
All my personal opinion, of course.
Iād be curious who all would be members of this in general. I havenāt done much in the Maw, though I know there are some NPC races in there apparently. I donāt remember all the NPC races mentioned, though I havenāt seen any reports of Saurok there at the moment.
Guessing it would be comprised of various spirits formed into the Maw and maybe some of the Mawsworn and purple Kyrians who changed their minds and side against the Jailer.
Of course, a new covenant means grinding the same stuff the other covenants have, so if it becomes true, itāll be fun to have to maintain 5 characters to see all their stories and stuff. x- x
Honestly, I really donāt know what to expect in terms of the Shadowlands storyline, but Iāll definitely keep my eye out for anything Ogre and Saurok related. 
