Heart Of Azeroth Essences
Corruption is going away in 9.0, but Azerite Armor and Essences will stick around
Corruption was the major gameplay system added to bring more depth and choices to itemization in Battle for Azeroth's patch 8.3, and it's seen a lot of updates, hotfixes, and changes since it went live.
A farewell to Azerite, Corrupted Gear, and the Heart of Azeroth once we’re in Shadowlands
One thing that's going to happen in Shadowlands is, we'll eventually shelve our Hearts of Azeroth and no longer have access to them or to the Azerite Traits that depends on them to work.