Actually that was their formula for Classic and it demonstrably seems popular. Keep the Red VS Blue story to a cold war and give us interesting monsters to fight in the meanwhile.
Faction Wars as a narrative don’t work here. Neither the Horde or Alliance can ever really win because of the nature of the game. So their fights should be in the background.
All faction war storylines are going to die in a miserable fashion as due to the nature of WoW - no one can win or lose. Not totally. There’s never going to be avenging armies marching through Orgrimmar or Stormwind.
Keeping the faction conflict to a cold war with flash points is the only sensible way forward.