It looks like The Karazhan Crypts will be in the game after many years.

[Putin-Chan]

.. But for Dk's only

Vampiric demons known as nathrezim forged this ancient sword, which brings with it violence, plagues, and death. Apocalypse soon earned a horrific reputation in the hands of a Tirisgarde mage who couldn't control its destructive energies. In time the sword was seized by the malevolent Dark Riders: servants of Medivh, the corrupted Guardian of Tirisfal. They hid the blade in the catacombs under his home, the tower of Karazhan.

The description of the unholy artifact.

[Deleted]

There is already thread about dk weps for legion

[Sylvaeres]

Not just for DKs, Locks also go there

[Sojourner]

Warlock: Affliction - Ulthalesh, The Deadwind Harvester
The first necrolyte to walk the world of Azeroth, Satiel, was given this scythe by the titan Sargeras himself. It grows in power as it draws souls from its victims. The Harvester earned its name as Satiel methodically drained all life from the hapless inhabitants of Deadwind Pass, creating a potent magical nexus there in the process. Hunting down Satiel, the Guardian of Tirisfal turned the scythe on her, sending her soul to join those of her victims. Eventually the Dark Riders recovered the weapon and secreted it beneath the tower of Karazhan.

[Warcrafting]

They also stated that 7.1 would have a set of Karazhan dungeons. Which means the Crypts will probably be one.