So in Legion we know what Genn and Sylvanas fighting each others and ignore major threat - Burning Legion. Its looks like most job doing we with our class hall and Khadgar. We also know what DK starting war with Paladins. We also know what DH is 12th class and 2nd hero class.
So i was thinking about what if after Legion blizzard make new 2 major factions and it will be not Alliance/Horde based but class based? I mean Alliance and Horde still be there but the players will be divided by class based factions. Some of classes make one faction and others do another? And they will be fighting each others like A/H. But players still will be available do story/quest/content from Alliance/Horde side. In legion we will have 12 classes - 2 of them is heroic classes. Something like:
Class Faction 1:
Death Knight - Warlock - Druid - Warrior - Rogue - Hunter
Class Faction 2:
Paladin - Demon Hunter - Shaman - Mage - Monk - Priest
I believe class factions rivalry will make lore easier to write because players will not be A/H and will can do quests/storylines from both sides. It also give each faction uniq based on class.