Back in 2013, Rockstar claimed to have "big plans" for new story content for Grand Theft Auto 5. Of course, this was well before GTA Online raked in a ton of money. In fact, the online mode for GTA 5 has brought in hundreds of millions of dollars since the game released.
As recent as last year, a GTA 5 voice actor had teased single-player DLC for the game, but a recent interview with Rockstar's director of design, Imran Sarwar, has revealed that the GTA 5 developers have moved on from their 'big plans' in an interview with Game Informer.
According to Sarwar, after a while, Rockstar felt like a single-player expansion for GTA 5 was necessary and it came down to three reasons why: 1.) The game is "massive," 2.) The next-gen versions took a lot of effort (so did reaching the "potential" for the "online component"), and 3.) Red Dead Redemption 2.
"No, it was not really a conscious decision, it’s just what happened. With GTA V, the single-player game was absolutely massive and very, very complete. It was three games in one. The next-gen versions took a year of everyone’s time to get right, then the online component had a lot of potential but to come close to realizing that potential, also sucked up a lot of resources. And then there are other games – in particular, Red Dead Redemption II. The combination of these three factors means for this game, we did not feel single-player expansions were either possible or necessary."
Somewhere in the middle of his quote, Samwar makes it clear that reaching the online portions 'potential' was more important than the single-player DLC, as was porting the game and making Red Dead Redemption 2.
Despite Grand Theft Auto V's lack of single-player DLC, Rockstar's director of design claims they are still committed to the single-player experience.
"We would love to do more single-player add-ons for games in the future. As a company, we love single-player more than anything, and believe in it absolutely – for storytelling and a sense of immersion in a world, multiplayer games don’t rival single-player games."
So it looks like you can take those GTA 5 single-player DLC hopes and transfer them to hopes that Rockstar supports Red Dead Redemption 2 with single-player DLC.