From Daelin Proudmoore’s wiki
He began raiding the coast and assaulting orcish settlements, but when they began to fight back he withdrew and retreated to the island citadel of Theramore. When he arrived, he was overjoyed to find Jaina alive, but found her keeping some strange company: Rexxar the Mok’Nathal, Rokhan the Darkspear troll shadow hunter and Chen Stormstout the pandaren brewmaster, all of them allies of the Horde that were with her. Daelin immediately demanded that they all be arrested, but Jaina retreated and helped Rexxar and his friends escape.
Unwilling to allow Jaina any explanation, Daelin usurped control over Theramore and used it as the staging ground for his newest campaign to have his vengeance on the orcs, but he was beaten back by their numerous allies, and was forced to retreat back to Theramore where he established a naval blockade around Theramore Isle to prevent the Horde from launching a counterattack. What the Admiral didn’t count on, though, was his own daughter siding against him. Jaina realized that her father was trapped in the past and that his vendetta against the orcs would only lead to more needless death and destruction for both sides, and aided Rexxar in destroying the ships.
The Horde then laid siege to Theramore and battled their way to his keep, where Rexxar squared off against the Admiral himself. Thrall tried to reason with Admiral Proudmoore, telling him that the Horde was no longer the same enemy he had fought so many years ago, but Daelin refused to believe that the orcs could ever change and launched himself into battle. After an arduous fight, Daelin Proudmoore, victim of his own hatred, was slain in battle. With his death, the battle ceased. Jaina knelt at the body of her prideful father and mournfully asked why he didn’t listen. Rexxar told Jaina to remember her father for the proud warrior he was.
What if Blizzard gives Jaina the same death as her father? Her naval forces bomb Orgrimmar from the sea and we battle her forces all down the coast. The battle concludes at Theramore where the effects of the mana bomb have weakened and she has heavily fortified. Rexxar squares off against the Admiral herself, Thrall tries to reason with her, but she refuses and battles us, and we have to kill her. Her last words are, “Why didn’t I listen? [to her father]” mirroring the words of her betrayal so long ago.
This could be Blizzard’s chance to kill off the green jesus as well, so that Metzen can finally be free. On a serious note, I think that a lot has to happen for this to become true. For one, Sylvanas needs to be deposed or willingly step down and Thrall needs to return. The Horde needs to appear changed, so that Jaina’s hatred appears “unreasonable” like her father’s was. (Even though her father was justified in my opinion considering his son was scorched in dragonfire and he witnessed entire kingdoms fall in his lifetime).