First off I want to say there may be some things within this post that some would consider SPOILERS. So if you are scared of that sort of thing don't read it and complain.
With that out of the way we can now get to it. So with 4.3 coming we know that Murzond is killed and is revealed to be a future version on Nozdormu. Upon killing him Nozdormu says this to you
"At last it has come to pass. The moment of my demise. The loop is closed. My future self will cause no more harm from this day on. Still, in the future, I will... fall to madness. And you, heroes... will vanquish me. The cycle will repeat. So it goes. What matters is that Azeroth did not fall; that humanity survived to live another day. All that matters... is this moment."
Now this would appear that this is the moment that Aman'thul showed Nozdormu or is it? When you kill Murozond or are killing him he says this
"You know not what you have done. Aman'Thul... What I... have... seen..."
Now this could mean this isn't the moment that Nozdormu witnessed that would be his demise. Or is this Murozond warning of us of the future and what the Titan's themselves have done are doing or will do to the world? Very interesting indeed. One thing I want to point out that this isn't the real demise of our Nozdormu is what found out in Twilight of the Aspects. This slight summary is taken from wowpedia.
After the battle Nozdormu took the time to explain that in one of the future timeways, he becomes the leader of the Infinite Dragonflight. Stunned, the three other Aspect listened as Nozdormu explained why he was late to the final battle: He was following another thread of information. He discovered who was behind the vast and dreadful conspiracy: The Old Gods. Nozdormu confirmed that they caused all of the horrible events against the Dragonflights and Azeroth.
Now note there it is "one" of the future timeways.. Also the fact that Nozdormu had to find out about the old gods being the corrupter is confusing because hiss curse is to know what is going to happen at all moments and not able to stop it. We also learned in Twilight of the Aspects that some how the Old Gods were able to get into the time ways and bring someone from one timeway into another just as we saw Thrall was able to travel in a completely different timeway, and most importantly we learned that there is one true timeway.
So my theory is that Murozond is a Nozdormu from another timeway which was corrupted by the Old Gods, and this explains how he was in a "future" timeway because in this timeway Deathwing actually won. Just like in Twilight of the Aspects Thrall was in a Timeway where he didn't survive and the world was completely different.
The Old Gods must know what is about to happen in the true timeway and want to stop it from happening they know we are going for the Dragon Soul and used their agent Murozond who controls timeways to try and stop it from happening. This would explain how Nozdormu had no knowledge of his corruption until he "found" it.
Of course I could be completely wrong and Nozdormu could just become the "new Deathwing" during the Deathwing fight. This being where the Old Gods latch themselves on to them. We will jsut have to wait and see. I just have a feeling that Blizzard would not let their most prized and interesting dragon Aspect simply get brushed off without adding an epic tale to it all.