That brings me to a thought. Let's say Chris "God" Metzen comes up to you on the street. He doesn't need a reason, he's Chris Metzen. He's awesome. And he says to you, he says, "Hey, I heard you like WoW lore. So I'm going to let you make a choice. You take any existing lore thread, and you tell me how to change. I can retcon whatever you want, or I can just make it go forward any way you want. You name it, I'll do it."
This is actually a pretty tough choice, but I'll throw one idea out of the mix (for me at least) right away. The Draenei retcon? I can live with it. It's not the worse retcon ever, and it can be hand waved away if you decide Kil'jaedan and Archimonde and their followers were already corrupt when Sargeras recruited them.
For me, what I'd really like to see is an embracing by the Horde of orcish culture and heroes before the Burning Legion corrupted them. One of the things that's always bothered me about Thrall is that while he says he speaks for peace, he honors the leaders of the wars against the Alliance. He wears the armor of the one of the greatest generals of those wars, and wields the hammer that killed Anduin Lothar, the greatest and most noble hero the Alliance has ever known. How can you truly say you want peace when you do that? I want Thrall to throw the Doomhammer into the Maelstrom and take off the armor. I can't believe all the oral and written tradition of the orcs is gone. Surely he can find some more ancient line of Warchiefs, Warchiefs who ruled over a more peaceful, shamanistic society, who lead the Horde only in noble wars. That is what I want to see, because that is what I believe the Horde truly needs to heal. They're too caught up in the darkest parts of their past as long as they continue to honor people like Ogrim Doomhammer and Kargath Bladefist. All that does is get them more Garroshes.
What about you? Where would you take one of WoW's lore story lines?