From Ancient Terra the Emperor commands His Proud Sons.
From revered Blood-stock these Warriors are made His Proud Sons.
No fear they shall know as Adeptus Astartes, His Proud Sons.
IMO if there is a change to factions, it'll be a single third faction comprising the "Heroes of Azeroth," lead by Jaina and/or Thrall. It will be an organization that transcends faction in order to fight major threats, founded based on the cutscene conversation between those two leaders. Players will still belong to the Horde or Alliance, will only be able to enter their faction's hubs, and will still be able to PVP and fight when it comes to inter-faction issues. However, there will be a core faction that will allow both factions to do instanced PVE content as well as possibly join the same guilds.
they're not going to ditch alliance/horde.
if they do more factions it's likely to be an aldor/scryers type additional faction system
i think that a guild as an overlying social construct (which ultimately doesn't have anything to do with lore anyway) could transcend three factions.
there would be a grace period in which players split themselves into the new factions. since i said game changer, it would shake up the whole comfort zone. city hubs would be re-distributed or lore-wise fought for a new leadership. what if the orcs would have to look for shelter in thunder bluff whilst the undead secure gilneas as a capital and the void takes orgrimmar?
i know, it is a lot of change and it could take a few months prior to the release or the full-fledged disband of horde and alliance. it could give the game a whole new vibe, a fresh start from within.
From Ancient Terra the Emperor commands His Proud Sons.
From revered Blood-stock these Warriors are made His Proud Sons.
No fear they shall know as Adeptus Astartes, His Proud Sons.
The Greater Anduinic Union of Azeroth. There are no other factions, just one huge stupid multicultural mess akin to modern, real world, unions.
That's how this all ends up.
All this positive discussion about potetially adding new factions? I'm all for it.
99.9% sure it's not going to happen. The other .1% will come from time itself.
Well in a 3 faction scenario the factions tend to auto regulate, as once 1 faction becomes too strong the other 2 factions team up. Alot of people think about DAoC and think this will work here as well, but they are obviously wrong, as that only applies to PvP in a very specfic combat scenario that involves true 3 way conflict.