I think how it will work is pretty easy to discern.
Anyone thinking that this change will involve the abolition of the Horde and Alliance is wrong. That is too drastic. Instead, I believe the following will take place.
1.) The Horde and Alliance are retained, they still hate each other and if you enter an enemy faction capital you will be attacked, just as now. The lore behind this change will be that the heroes of Azeroth, the players, are capable of putting their mutual hatred to one side for the greater good. Their factions will not be.
2.) You can now communicate with the other faction and everyone is free to join their preferred guild, regardless of faction.
3.) You can invite a player from the other faction if warmode is off. You can participate in dungeons and raids together without restriction. Some instances have Horde or Alliance themed content, such as the 3.3. dungeons where youâre accompanying NPC was determined based on your faction or BFA where the Battle of Dazarâalor had different faction versions. The version of the instance you enter in those cases will be determined by the faction of the party leader.
4.) If you invite a player from the other faction, the ability to turn warmode on will be disabled so long as that player is in your group. If you have warmode on, the ability to invite player from the other faction will be disabled.
5.) To preserve the faction vs faction nature of battlegrounds, you will be unable to queue for either random or rated battlegrounds with a member of the opposite faction unless the member of the opposite faction enables mercenary mode.
To me, this is the surgical intervention required to remove the current difficulties. It preserves warmode, preserves the Alliance and the Horde, restricts the faction rapprochément to players only rather than getting everyone in the story involved and offers everyone the choice to play what they want with whom they want. The only restrictions are on PVP battlegrounds, and that is to preserve the character of the battles which I feel is an important aspect of those fights AND it is merely a requirement to activate mercenary mode to play with your friends in PVP.
I think this would please the vast majority of people and not overly undermine the faction divide. As a fan of having two distinct factions I think it is important they are preserved as much as possible, but I recognise mismanagement of the factions means something now needs to be done for Alliance players.