I've been thinking about this, and it is very clear that the Horde is in a huge disadvantaged.
1. With the Siege of Orgrimmar, the orcs are not anymore the most powerful army on the Horde.
2. The lightforged Draenei have a friking spaceship, with the power of the crown of the Triumvirate. And they have advanced technology.
3. The Alliance have Malfurion, Tyrande, Velen, who are really strong by themselves, and Anduin, who apparently have super strength, and none of the Horde leaders have that kind of power.
3. Nightborne no longer have the nightwell, so they lost their capacity of being a strong addition to the Horde.
So, how do you think the Horde will manage to not being destroyed in the first patch?
P.S. Sorry for the broken english.