With no archdemons or giant cosmic cthulian monstrosities on the immediate horizon, we will be fighting each other. The alliance and horde have very diverse casts of characters and I know I can't be the only one curious of the sort of conflicts we might see. Remember Sylvanaas and Greymane?
One that comes to mind is the pandaren factions that joined the alliance and horde. Currently Ji Firepaw and Aysa Cloudsinger train side by side in the monk order hall. How will the pandaren, who were so devastated by the last horde/alliance war react to this one?