The faction split has been dead for years. Just think about it for a second: The area of the game where the faction split SHOULD be most important is obviously PvP - but there is mercenary mode for random BGs and rated PvP ignores factions.
The only area of the game where a faction split exists is for PvE, where everybody fights the same monsters for the same reason anyway. Yes, that includes Warmode, as Warmode the way Blizzard implemented it is only about WQs and nothing else....and WQs are PvE content.
The way factions are working right now - where they are disabled for the content where they SHOULD be the deciding factor and only enabled when you could team up to fight monsters for the same cause - is not beneficial to the game in any way that i could see.