I've been digging through new WoD Lore for the past weeks and learned some cool new stuff on which i will now speculate.
Basically, i've been questing through Spires of Arak and it is really a cool zone which is really story driven and reveals a lot of stuff regarding Arakkoa lore, which is a pretty interesting subject.
To give a short update for those who haven't read up anything on this.
There are 3 groups of Arakkoa
1.Flying, uncorrupted Arakkoa worshipping Rukhmar, the sun goddess of the Arakkoa, which has the form of a fire bird
2.Flightless Arakkoa, who worship Anzu and have to hide from the flying Arakkoa because Rukhmar deems them unworthy
3.Sethekk, Flightless Arakkoa, who worship Sethe, a dead flying serpent god (Ever wondered why you find flying serpents in Sethekk halls? There you go)
The history goes like this, Sethe being a evil god and such, cursed Anzu into flightlessness, in return Anzu sent his Dread Ravens to slaughter every single flying serpent and afterwards Anzu & Rukhmar defeated Sethe.
Anzu, being unable to fight this curse, disappeared into the shadows and handed the lead of the Dread Ravens over to his mate.
However, Sethe's Death created a place called "Sethekk hollow" which is filled with his blood and any flying Arakkoa who enters there turns into a flightless Arakkoa, the flying Arakkoa use this as a punishment for people who act against the will of Rukhmar.
There is more to Arakkoa lore, but i'll this one out, the wowpedia articles of the Spires of arak questing is close to complete in regard of Arakkoa lore, so you can read up there all the stuff if you want.
http://wowpedia.org/Spires_of_Arak_storyline
You also meet Admiral Taylor, but be prepared to see an NPC model you haven't seen for quite some time.
But how this relates to Hakkar and the Emerald Dream?
During Spires of Arak questing it is also revealed why the Sethekk want to bring back Anzu, in alternate Draenor they seek to bring him back so that Sethe can bring him under his control and use his powers to conquer Draenor.
Now it is quite likely that this was also their actual Plot in Outland, bringing back Anzu so that they he can be enslaved and used to conquer Outland.
But the Sethekk started to worship an Old God in Outland, right? it fits because the Aspect of Raven, that is encountered during the Druid epic flightquestchain yells the following:
http://wowpedia.org/Quest:No_Mere_DreamFoolish druid! Dividing your essence has weakened you, opening the door for my master to dominate the Emerald Dream. Your spirit and body will die here!
So the idea was probably that Anzu being summoned in Outland is supposed to be enslaved by the very Old God that the Sethekk now worship.
It is also revealed during the Druid epic flight questchain that Anzu is causing trouble in the Emerald Dream, which is a mystery because no one knows how he has access to our Emerald Dream.
There is also this prophecy from the Druid epic flight questchain:
http://wowpedia.org/Quest:The_Book_of_the_RavenFrom the dreams of his enemies shall the raven spring forth into the world.
But now to Hakkar, Hakkar is a Loa, the Loa of Blood to be specific (http://wowpedia.org/Questark_Vessels_%28Alliance%29), has possibly access to the Emerald Dream as well, right?
Many Loa do have access to the Emerald Dream, as it is a core reason why Darkspear trolls were able to become Druids, Troll Druids even call most Ancients, which have a deep connection to the Emerald Dream without a doubt, Loa as well.
Hakkars connection to the Emerald Dream, or rather Nightmare, is probably even deeper than most other Loas, as seen in the Sunken Temple you had some business with some corrupted Emerald Dragons within a temple dedicated to the worship of Hakkar.
But questing in the Swamps actually shows that the Atal'ai use Emerald Dragons, which are injected with Hakkars Blood, then can be used to cause some foul powers to manifst within their corpses. (http://wowpedia.org/Quest:Step_Two:_The_Bloodletter) This "foul" power could obviously be related to the Emerald nightmare, considering the circumstances.
The theory that Hakkar is an Old God or at least in a relation to an Old God isn't new, while there hasn't been any confirmation on this, the connection between Old God(s) and Hakkar still exists.
But in the end, how does this fit together?
Could Sethe be the Draenor equivalent of Hakkar? The similiarities are there:
1.Both are serpent gods
2.Both have powerful blood, Sethes blood curses Arakkoa into flightlessness, Hakkars blood is quite corruptive and can be used for empowerment
3.Both are gods to a race which views them as evil but is still worshipped by a small portion, Hakkari / Atal'ai <-> Sethekk
4.Both try to enslave the other gods, Hakkar held the power of other Gurubashi Loas through their highpriests, Sethe wanted to enslave Anzu
Now, for this to fit together, is it possible that the Sethekk sent Anzu into the Emerald Dream with the help of Sethes blood?
For this to work, we need 2 criterias:
1.Did the Sethekk had some blood left of Sethe after the destruction of Draenor? Unknown but possible, i can imagine that they used his blood in some kind of charms or simply saved something before Draenor fell apart.
2.Did they learn of the Emerald dream? Unknown but possible once again, considering that they worshipped an Old God in the end may gave them more knowledge than we might know, obviously the aspect of raven yelling points towards that Anzu / his aspect was already under the control of something that sought the domination of the emerald dream.
They also might have learned of the emerald dream from a druid that came through the Dark portal, the prophecy posted above possibly also known to the Sethekk, so this might have the thing they have been waiting for.