Obviously, the Shadowlands will be eventually restored to some kind of order -- and Sylvanas will very likely be defeated, one way or another. But what about afterwards? Bolvar is now freed from Icecrown -- and either he stays in the afterlife forever, or he returns to Azeroth with its heroes.
1. Bolvar takes the mantle of Jailor -- just he was Jailor at Icecrown for so many years -- after the current Jailor is inevitably defeated or banished somehow. He spends the rest of eternity trying to restore what he has broken, trying to improve the system and simultaneously containing the Jailor and Sylvanas if they still exist as well, and presiding over the newly forged cosmic balance with the help of the reunited Pantheon of Death, which he himself joins.
2. Bolvar returns to Azeroth and rejoins the Alliance as a death knight and advisor to Anduin, much like in the old days, but perhaps from the shadows. His ties to both Anduin (his son in all but blood) and to Taelia (his only daughter in blood) are too strong for him to ignore, especially free from his former duties, and he goes back to Stormwind. After all, they probably reluctantly accept death knights into their ranks by now, or at least are somewhat used to their presence in their ranks, such as Thassarian openly fighting in the Alliance military.
I think they might have possibly changed the text or something -- but Bolvar does still acknowledge Anduin as his king in this quest.
https://i.imgur.com/2aEtw76.png
3. Bolvar returns to Acherus, the Ebon Hold, and continues to lead the death knights, but withdraws from Azeroth's affairs. He remains a largely neutral NPC -- and is largely forgotten or ignored after this expansion, not unlike some other characters from the previous expansions who have faded away into irrelevancy.
Which of these options is most probable? Or something else entirely? Which would you personally prefer to see happen to Bolvar?