It's here to stay.
It turns out that there’s a 6 vs 6 Lockout Elimination game mode now live on the Arcade.
A 3 vs 3 Lockout Elimination game mode was introduced with the recently concluded Overwatch Anniversary event. We reckon Blizzard saw that players were getting a great deal of enjoyment from the new mode and decided to keep an expanded version in the base game.
Check out our Lockout Elimination Guide if you want a few ideas on how to gain an advantage in this new game mode.