I think its safe to say that Mag'har Orcs will be Horde Allied Race from AU Draenor. But
Alpha Build 26032 have some interesting lines about Gorgrond zone map:
I'm not sure how two battleships makes it into AU Gorgrond by sea. But this lines hints that Alliance also going into AU Draenor in search of allies. So I was thinking what Alliance Allied Race can be there. Some people were talking about Saberon, others about Dark Iron that have base/outpost there.
But what if its Gorian Empire ogres?
WoD and Lords of War make its pretty clear that AU Orcs and Ogres were at each others throats and hated each others. It was told that Imperator Mar'gok allied with Grommash's Iron Horde only because alternative was extinction. So now with Iron Horde and Gorian Empire crushed nothing stops survivors of both sides continue to hate and kill each others.
Lets imagine for a second that Horde recruit Mag'har and Alliance their hateful opponents Gorians:
1 - Gorians will be perfect match to counter Mag'har if we talking about "enemy of my enemy".
2 - Ogres are seafaring nation and had great naval fleet. Speaking of importance naval power and experience in new expansion.
3 - Ogres are powerful magic users. Imperator Mar'gok even had his own magic breakers. Alliance finally will have something to counter Horde dominance in magic field.
4 - They not just savages. Their concept was based on Romanian Empire.
5 - They possibly befriends with Dark Iron because both share same views. For example both Empires approved slavery and had magic ruling society.
So Alliance players - would you like to have Gorians Ogres as Allied Race? I know MANY Horde players will say Ogres belong to Horde and will never join Alliance. Remember High Elves? With Blizzard you never knows...