I don't think the next expansion will be 'The eye of Azshara' as the trademark which they made nearly a year ago would suggest.
Gul'dan! *He yells in pain*
You made a pack!
Archimond then banishes Gul'dan back through the portal (to the twisting nether).
Some talk happens then Khadgar walks over to Gul'dan's staff and it disintergrates.
See in our wow universe there was someone else who was banished into the twisting nether for failing the burning legion.http://wowwiki.wikia.com/Kil%27jaedenKil'jaeden tricked the elder shaman, Ner'zhul, into thinking that the draenei were plotting against the orcs, and subtly introduced warlock magic and bloodlust to the clans.http://wowwiki.wikia.com/Lich_kingWhen Ner'zhul attempted to escape Draenor, he was immediately apprehended by the demon lord Kil'jaeden, who enacted the blood pact that Ner'zhul had sworn many years earlier. Kil'jaeden ravaged and destroyed his body, but kept his spirit alive and encased it in a block of ice from the Twisting Nether. Kil'jaeden granted him increased power, including that over death itself. Ner'zhul ceased to exist, and the Lich King was created.
Ner'zhul was defeated outright in the WoD alternate universe so the Lich King could never be created.
With out a Lich King we shouldn't forget this:With out its master's command, the wrestles scourge will become an even greater threat to this world. Control must be maintained, there must always be a Lich King.
So here is my prediction: maybe Gul'dan to be the Lich King in the alternate universe? http://wowwiki.wikia.com/IcecrownThe name of Icecrown became infamous when Kil'jaeden hurled the Lich King back into the mortal world. Ner'zhul's prison slammed into the glacier and created the Frozen Throne.
So the location of the next expansion pack could be an alternate version of Northrend. I know that one of Blizzards biggest regrets was not to have an underground Ahn'kahet zone and this would be an opportunity to provide it. Also, it would be interesting to see if Bolvar Lich King interacts with things somehow and maybe even unifies the 2 universes.
Further on beyond that expansion pack Northrend has many links to the old gods. The under the sea expansion pack featuring Azshara would link well from a new Northrend expansion.