Didn't read all, but I would like something like this:
We lose against the Legion. Slowly they invade all of Azeroth and destroy it place after place. As Players, we do all we can, fighting all over the world, but at some point there is no help. While we are on the brink of destruction all the mages and engineers work like crazy on some kind of ships/arch whatever, that we can flee the dying planet. The endvideo shows how the ships take off and leave in deep space and a last look through a window shows a big explosion that was Azeroth.
Then WoW 2 starts a while later, on a space station build together from the leftovers of our ships with our character again at lvl 1. From the space station we search and explore for planet(s) we could live on and have to conquer them, fighting against <insert random evil>.
Maybe someone can fill the holes in history, to make it a reasonable story.