Essentially this.
Spoilers Below for those who haven't played RDR1:
While there are some plot holes and questions I have about the overall narrative, the Red Dead series is one of my favorite series of all time. I've replayed the entire series (1 and 2) several times listening to dialogue and encounters and immersing myself in the world. One question that always eludes me was, "Why did the government or the Pinkertons give up after John died? Abigail was a thief and had quite a history too. Going back to Red Dead 1 it's mentioned that the "high ups in government" (Edgar Ross during Prologue I think?) was looking to get re-elected and the problems of the past needed to be finished up and dealt with. To this end the Pinkertons were once again let off their leash and given orders. Edgar Ross who remembers all to well the trouble the Vander Linde Gang caused and the death of his former boss and friend Mr. Milton knew where John was and that John had a family. Furthermore, the death of Micah Bell (I'm assuming Ross learned that it was John who killed Micah), further helped Ross see the potential to "Use" John to track down the rest of the gang.
But like all that stood in the way of "Progress" who refused to go away, John too was a member of the gang and had to go. Throw in the added element of abuse of power and corruption and for me at least it's not hard to understand why John was betrayed by Ross in the end (I believe Ross offered him a full pardon for him and his family to sugar coat the deal in the beginning?).
In my head cannon, I like to think that John's last stand and sacrifice at the end mirrored Arthur's to a degree but had the final caveat of drawing attention to the abuse of power by the government and the pinkertons. I like to imagine that because of John's end, the corrupt officials didn't get re-elected and the the Pinkerton's were put on the road to removal. This final act by Arthur and then John were the nails in the coffin for government overreach and abuse of power (At least for a little while). Because of this, Abigail was never rounded up and dealt with either. The sorrowful and yet interesting aspect comes in the form of Jack Marston who killed Ross despite his father and the gangs best efforts and wishes for a different life for Jack. I guess in my mind this goes to show that Ross's past couldn't escape him just like the gangs.
The Above is my interpretation of the story and shows that at least to me and those like me, the story of the first and second games is well loved and will always have a special place in our hearts.