E3 approaches. The endless tide of GTA 6 rumors keep on coming, spawning continuous speculation among the fans. Debates on what non-GTA franchise Rockstar should revive as their next big project. Will it be Red Dead Redemption 2? A new Manhunt or Midnight Club game? Maybe even Bully?
Thing is, we might not find out for years to come. What if Rockstar's bug E3 reveal is just a groundbreaking and massive update for the current iteration of GTA Online, such as the inclusion of new cities?
Let's face it — GTA Online is a freaking juggernaut in terms of business. It has a massive dedicated and active playerbase, it's driving up sales and generating absolutely massive amounts of income.
We've often talked about how Shark Cards have made over $500 million in profits for Rockstar, but it feels like the significance of that is somehow understated. Most games — even Rockstar games — don't ever make that much money. At all, let alone from DLC. Let alone from microtransactions!
The fact that GTA Online stands as a constant source of steady, high amounts of income with minimal input required. Even the larger DLCs like Executives and Other Criminals require a tiny fraction of effort to make compared to the whole game.

GTA 5 has made $3 Billion in profits since release. The first billion was made within three days of release, when Online wasn't available yet. However, looking at forums and the Subreddits show that an overwhelming number of players, or potential player bought the game solely for the Online component.
So, let's count with $1.5 Billion thanks to GTA online, Shark Cards included. The game's budget was $265 million, meaning it has already returned a massive profit. The constant stream of free updates for the game are funded by a constant stream of income from continuous sales and microtransactions.