I'm thinking "his own purposes", is (in his mind anyhow) safeguarding the world from reckless arcane usage. After the events of the sunwell unfold, I'm sure he'd be more determined to reign in "unregulated" use of magic.

As they say, the road to hell is paved with good intentions.

And considering the other Dragonflights wouldn't even kill -Deathwing- because they were afraid of what would happen, I can't imagine we'll destroy him either. It apparently is the Warcraft equivalent to crossing the streams.

There's just gotta be something we don't know yet.

Mad mad Malygos, did I miss the lore that gave him his flight back after Krasus stashed them for him? I thought the hope was that regaining his flight would help him recover his wits a bit?

Speaking of Krasus I really hope he and Alexstraza play a large part in the lore of Northrend. I would hope that the quests surrounding the shrines in Dragonblight would allow us some access to interaction with each of the flights.

As far as the commenter below asking how Outland will fit in with Northrend, there are several threads that have been prepped by Outland which we should be able to follow in Northrend.

One of which is the relationship of the black dragonflight to the netherdrakes. Another would be the Sunwell opening in Northrend and the obvious presence of the Scourge and the Burning Legion that are involved in the daily quests surrounding SSO as well as in MrT and SPLAT. And possibly the reuniting of the 3 Windrunner sisters (Alleria, Sylvanas and Vereesa). There are a lot of ends at loose yet.

Don't forget the Ashbringer! That likely will tie back to Outland as well.

It's an MMO; you'll always progress past things to whatever is 'endgame'. But Blizz figured out decently early in TBC that we wanted to have some stuff in the old world as well, and likely there will be things to do in Outland in WotLK too.

Actually unlike the fall of Keal'thas you could see the fall of the Blue Dragon Aspect in the novels "Day of the Dragon", "War of the Ancients"

And in retrospect any of the Lore that follows by meeting Tyrygosa (might be spelled off) in Netherstorm near where all those Etherium people are located.

She's out there taking control of a clutch of Netherwing Dragons (who use to be Deathwings Black dragons btw) to help restore the memories that got deepfried in dear daddy Malygos' big old dragon noodle by the Demon Soul.

Considering that the essence of the Netherwing Dragons is Nether Energy. I think the combination of Losing ones flight, watching the mortal races abuse the gifts HE gave to them, and then having his mind restoried by a foreign power is enough to turn anyone crazy.

Who knows maybe like this old friend Neltharion, he's hearing the whispers of the "Old Gods" too.

I really do hope we get to see More of the Aspects in this game.

The Machine part makes me wonder. But then again given that 2 blue dragons appear at the Sun Well, and there are blue dragons in outland. Who knows what they returned to dear old dad with to share on their adventures.