I would update Dustwallow Marsh and the Hinterlands.
For Dustwallow Marsh, I would have Stonemaul Village reclaimed and converted into Stonemaul Fortress. Brackenwall Village remains as a Stonemaul/Horde outpost, while Horde Grimtotem loyalists arrive and seek to sway the Grimtotem in the region away from Magatha. One camp will join the Horde, the other will remain loyal to Magatha.
The Ruins of Theramore are claimed by rogue wizards, while Alcaz Island is claimed by the Alliance to keep an eye on the region.
Horde storyline is centered around the Stonemaul reinforcing their holdings and the Grimtotem civil war. Alliance storyline is centered around trying to figure what is going on in Theramore, while securing their holdings, and spying on the Stonemaul.
As for the Hinterlands, my revamp is centered around the Revantusk tribe. Jintha’Alor is firmly established as their new capital, with Elder and Primal Torntusk in charge, while Huntsman Markhor is now in charge of Revantusk Village, which has a boat path to both the Echo Isles and Zandalar.
As we quest in Jintha’Alor, we discover that the Revantusk were in talks with the Smolderthorn and Firetree tribes, who have left the Blackrock Mountains for greener pastures. By the time we arrive the Firetree have joined the Horde and joined the Revantusk in Jintha’Alor. However the Smolderthorn, led by a living War Master Voone, are more hesitant.
From Skulk Rock, the Smolderthorn are courted by both the Horde and an unexpected Vilebranch - Witherbark alliance. After a series of events, the Vilebranch and Witherbark launch on all out attack on Jintha’Alor, as the Revantusk and Firetree defend the city. During the attack we receive word that the Smolderthorn are on the move, with both sides uncertain as to what decision Voone will make.
A cutscene will then trigger, where Voone and the Smolderthorn are revealed to have come to aid the defenders of Jintha’Alor, in the vein of Gandalf and Rohirrim saving those at Helm’s Deep.
In the aftermath, the Witherbark are revealed to have fled, while the surviving Vilebranch fought to the bitter end, a grim end to a dark tribe. As the three tribes establish Jintha’Alor as a united Forest Troll capital for those who serve the Horde, with the leaders forming a council to help govern the city.