Keyring

Exact functionality and appearance of is not known (it might be an item or just a specialized new bag slot), but it will hold some number of dungeon keys.

Source
From :  We're pleased to announce that the keyring functionality has been completed and will be in place for patch 1.11. When a player first acquires a key, they will automatically acquire a keyring that will hold permanent dungeon keys. The size of this keyring will increase as the player goes up in level -- as seen below.

Level 1-40 = 4 slots Level 41-50 = 8 slots Level 51-60 = 12 slots