Rockstar has opened up about yesterday's tease sooner than we had expected — the Diamond Casino Heist DLC has just been officially announced! Coming to Grand Theft Auto Online on the 12th of December, this will be the last major DLC of 2019.
The Diamond Casino Heist is a large, daring scenario that might upend the typical narrative structure of GTA Online content for the first time. We aren't quite sure how this is going to play out, but the main goal is to break into the Diamond's vault. That said, you are still working with Baker and the Chengs against the Duggans.

Do the Duggans succeed in taking over the Diamond in spite of your efforts in the previous DLC? Will the Diamond be temporarily unavailable to players? Is this all a ruse, a "fake" heist designed to make the Diamond look less valuable to the Duggan oil magnate family?
Whatever direction this new DLC takes, Lester Crest will definitely be involved, helping you orchestrate the most daring heist Los Santos ever saw. Players will need to operate out of a new DLC-specific property. This time, you'll launch and run a retro Arcade business, but it's all just a front for your heist-planning nerve center. While customers are busy racking up high scores, you'll spend time in the basement practicing lockpicking and hacking.