Yes its early to think about this but here it is anyway...
With MoP being based mostly on the alliance/horde war (unless I've been reading the info wrong) what do you guys think about teaming up for the final tier of the expansion. (and maybe some other things)
Every end boss is been some monumental thing that has endangered the entire planet and while the only instance that I remember seeing both factions actually doing something is the gunship in ICC and a few times where NPCs were talking.
So what if there was basically a joint operation of the 2 factions? Get that server participation back that hasn't been seen since the days of the Ahn'qiraj opening. Id imagine that at some point our faction leaders would get there shit straight and be up for the idea after quite a bit of persuasion.
It could open up a lot of fun things to do. Allow instances where one team downs a particular part, and the other team contributes in a different way. Then change it up the following week.
Ex: Week 1. Alliance fight a giant type boss. While they fight the boss on the ground, taking out adds, destroying legs and making him wobble, the horde would be in a gunship and hitting him in the eyes so he can't see and doesn't just run around stepping on people like a giant would.
Week 2. Vise Versa.
If its to difficult to get a horde and alliance raid being set up at the same time, then just have a NPC raid that can basically just do what the opposite faction would do for that raid. But allow a system that if 2 raids want to try and get together and do it they
Communication wise, have a horde and alliance leader being present at the fight, and allow each faction to talk to the other through their said leaders.
Getting 2 different sides of the instance would keep it from getting boring as hell and drawn out like most instances have become near the end of tier.