the burning legion conquers the void lords and enlists them into the fold, with their greatest and most hated enemies now apart of the legion the ethereal can stand by no longer and decide it is time they take a side in the war to end all wars.
the consortium and its trade prince has decided to stand firm in their decision to remain completely neutral between the horde and alliance but the other trade princes refuse to work together only communicating using the consortium as a surrogate, divided they cannot stand against the legion so two trade princes decide to join the horde and alliance and reach out their hand to help in the war effort and supply them with technology and weapons.
steadfast in their beliefs and practices the protectorate refuse to stoop to the level of the etherum and have thrown their lot in with the alliance, disgusted by their rival traders the goblins and amused at the gnomes technology they feel they're work will be most appreciated and respected in the alliance.
their trade prince has rebuilt the lost park in stormwind into a transdimensional transporal dimension ship filled with markets, trainers, and many vanity goodies like pets and mountable animals they have encountered in the cosmos, and yes it is bigger on the inside (this is assuming blizzard doesnt rebuild the park by the end of mists)
Refusing to work with the protectorate and believing the alliance is being to cautious with the way they battle the legion the ethereum has made an arrangement with the brutal horde of azeroth. in exchange for weaponry the horde will give them powerful artifacts and scrolls of lore so that the ethereum can re-engineer and retrofit azeroths own unique forms of magic to suit their needs, like when the blood elves joined the ethereum look down upon the primitive races of the horde and in fact all of azeroth, they hold themselves in high regard and this alliance of necessity is little more than a business deal to further their own power in their eyes.
their trade prince has build a floating ship just outside orgrimmar near the gate to azshara, it is a meager ship filled with but a few "diplomats" and a stable of exotic beasts and creatures they believe will distract and amuse the primitive races of azeroth.
the ethereal will have access to
death knights - the ethereal have managed to re engineered the magics death knights use and while not true death knights since they are already walking spirits being held together by magic they wield the same powers
no shamans or druids. the ethereal see no reason to communicate with the elements and they make use of eco domes having no need for druidic magic.
the ethereum find the warpstalkers ability to warp in and out of reality very pleasing when it comes to ambushing their prey and the warpstalkers ability to disrupt magic make them perfect against the magic wielders of the legion
giant armadillo for the protectorate (in my idea they would have giant spiked ball tails as well)
the protectorate respect the tough hide of the armadillo and its spiked morning star esque tail can rip through the armor of even the strongest fel reavers.
they start out aboard a transdimensional ship as a member of the consortium, they stop down on a near barren planet to make a trade deal with emissaries of the legion, as they are talking and making completing the deal void soldiers ambush the consortium, slay the dealer and steal the supplies. you are the only survivor.
you return to the ship and inform the trade prince and you discover that it was a trap by the burning legion, filled with rage the consortium sends a message to all other trade princes for a meeting and to stop all trade with the legion.
they all meet on outland where after arguing they all decide it is time they choose a side and fight against the legion, while there they are again attacked by the burning legion and forces of the sha tar draenei for the alliance and the maghar for the horde still stationed in outland help them defeat the legion.
the consortium decides fully putting their forces into fighting the legion isnt a sound plan and decide to continue as is while in the shadows sabotaging legion activities when the opportunity arises.
outraged by their inaction you hear the protectorate and the ethereum are joining the horde and alliance to fully combat the legion. you speak to each trade prince and they tell you that once you swear fealty to them you may never again rejoin the consortium or change your mind and join the other side or be labelled a traitor and have a bounty put on your head.
you swear fealty to the trade prince of the ethereum or the protectorate and then you arive in either stormwind or orgrimmar where if you join the protectorate you meet with varian and prince velen who decide that with this new alliance they will be able to not only take the fight to the legion but hit them hard and before you come in you hear varian speaking with velen about receiving word of turalyons return and new information about the legion before you interupt them.
if you join the the ethereum you arrive in orgrimmar and are there to witness the deal between the new warchief and the trade prince of the ethereum, you have the honor of presenting the warchief with the contract and with a bit of hesitation he/she agrees to it. before you come in you hear the new warchief speaking with an goblin spy who says they spotted alliance heading out to a portal in order to fight the legion.
refusing to be left behind the horde mobilizes and races to try and get there before the alliance does.