Simple as that - should there be another faction war on a scale of Cata or BfA? And not just some skirmish on the border that is forgotten a week after it started and ended after both parties got tired and went to the tavern but an actual warfare with both factions actively engaging in it.
Personally i cant stomach any more of that stale crap they call "war" which makes me actually loathe it (which is the first game about war that made me feel this way) (maybe thats because i mostly main night elves which makes me feel like i am not fighting but rather being gassed in a "shower room" each time war starts).
But at the same time i fucken crave it since the only way for Alliance to actually move forward without night elves and worgen ejecting from it is to wage war and avenge the BfA in some absurdly bloody murder fiesta.
Which will also allow Horde to have some moral parity with Alliance, maybe waging war honorably, even if at the cost of quickness of their campaign or something like that. Not "hampering" themselves but also visibly slowing down because they refuse to sunk to "Old Horde/Sylvanas" level and mass murder civilians or burn down populated centers instead of taking it more conventionally.
While Alliance can have "madness of war" narrative when we see many characters broken by BfA, now only wanting to either even the score by slaughtering and burning as much as they can or seeing horde as potentially too powerful and calculating that only a "culling of the Horde" (herd pun, heh, look i am funny...) can save Alliance's future. Which will also hamper them - all that civilian hunting, executions, enslavement and such will slow down the advance while making locals and maybe even neutral forces refuse to cooperate with Alliance since they see their acts as empty hatred and waste of life.
In the end we can finish it all off with either a huge battle after which both factions can fight no more , not just "oh we kinda low on troops" but actual depiction of a battlefield littered with corpses all the way to horizon with faction leaders bloody and dying there, when there is no hands left to fight and swords and axes are blunted and broken.
After that they can either make both factions cut ties forever, Horde doing so because they dont want to "continue the cycle" and Alliance doing so because they cant stand the Horde and see them as absolute monsters OR because more "goodie" leaders of the Alliance see their own faction as no longer right in this war.
Or they can throw in a big bad who will take down both factions, maybe not a "Big Bad" as a singular figure but some organization or "order" which grew in secrecy, maybe even using this war to recruit more people into their ranks since "Horde and Alliance are at it again, see, they cant govern Azeroth! But we can..."
Frankly speaking i am tired of war, and have little faith in writers (scratch that - i have NO faith in them) but now, all the way since BfA there is simply no other feasible way for factions to coexist. Yeah, even with Horde Council in place, you heard me. At this point Alliance forgiving the horde will lead to Alliance (at least logically) losing several member races and as a player i cant stand looking back at BfA. It was a travesty and it can only be remade in blood, guts and absolute agony to even the score and THEN throw the war narrative out entirely.