Alrighty, so here's what I've been thinking since about a week into Warlords of Draenor.
I think we, the Horde and Alliance, are the ones that cause Outland to explode and by doing so will make us have a self-fulfilling time-line. And by that I mean that there are certain fixed points in time and time makes these events happen whether we try to change it or not.
Outland was destroyed by:
"Outland was created when Draenor became the focus of an attack, via the Dark Portal, of an Alliance expedition aiming to end the orcish threat to Azeroth once and for all. In the midst of the ensuing battle the Elder Shaman Ner'zhul attempted to allow the remaining orcs on Draenor to escape to other worlds by opening other dimensional portals; however the presence of so many portals tore the planet apart, leaving only torn fragments of the former world floating in the Nether, and the barely-habitable remnants were renamed Outland. "
Now I'm not sure how many portals it was, I imagine it was quite a lot.
Theory #1: (Low Probability)
-During this time-line we're the ones that open up too many portals.
Theory #2: (Higher Probability)
-Each faction gets overwhelmed by the Iron Horde to such a degree that the only way to save us is by allowing Ner'Zhul to unleash the Burning Legion upon Draenor and then use the method we know works for destroying Draenor to trap both Burning Legion and Iron Horde on the planet. Therefore saving our timeline from both threats.
Just wanted to talk about it if any of you guys are interested.