Rockstar Games seems almost entirely uninterested in producing single-player DLC for setting player count records? It's a shame though, since both major expansions for GTA 4 and Red Dead Redemption's Undead Nightmare were so well received. Although GTA Online is clearly Rockstar's money maker, it's still a bit strange that the most recent games they have made, with such a heavy focus on single-player, never get any more single-player content, even though it is almost guaranteed to sell well.
Perhaps it has come down to the amount of effort required to create a whole new narrative, new assets, hire voice actors, come up with unique content, etc. A good way for Rockstar to at least partially satisfy the many fans petitioning for RDR2 single player DLC would be to remake the first game as an expansion. Not only would people be thrilled to replay the classic with a new coat of paint, but it would be a huge step in unifying the one, long story that spans two games. Additionally, this would be the best way to bring the first Red Dead Redemption to PC, that way those who never played the original have a chance to experience it without a downgrade in graphics and gameplay.
A PS5/Series X remake of Red Dead Redemption has been rumored, but so far nothing has been confirmed. The idea is almost a no-brainer, since the Red Dead Redemption games are widely beloved and it will certainly be a long time until another entry in the series is made.
The Red Dead Redemption Saga is Ripe for Unification
The good news is that RDR2's epilogue and seen its version of Armadillo in 1907, they can move on to 1911 and watch John get off the boat in Blackwater and begin hunting down the Van der Linde Gang.
Of course the Mexican region of Nuevo Paraíso will need to be added, since it is not present in RDR2. The first Red Dead Redemption is certainly starting to show its age, since it was released over a decade ago in 2010, and could really use an new character models and animations. Offering the first game, remade as an expansion for Red Dead Redemption 2 in order to let people play through the entire story, nearly doubles the amount of single-player content available, and fans would undoubtedly turn up to buy it in droves.