The Horde stole the focusing iris and used it in the manabomb, and Kalecgos helped the Alliance try to defend Theramoore, so it'd be pretty fitting for them to mingle more openly, particularly since Alexstraza swore an oath to the wildhammer dwarves, high elves, and humans in Day of the Dragon...
That'd free the Horde up to get aid to counter the dragons, perhaps Nerubians or Gronn, what do you all think?