6. The Main Character Is A Marshall Or Sheriff
A key element of just about every Rockstar game is that the player is always very anti-law enforcement.
Whether you're pulling heists in GTA or slingshotting prefects in Bully, the games' main protagonists are hardly a representation of any law-abiding citizens. However, if Rockstar showed anything with L.A Noire, it's that being a law enforcer CAN work (if done properly). With one recent theory offering up the possibility of RDR2's protagonist being a law marshall or a sheriff, law enforcement itself may become even more appealing than ever before.
What would set this potential scenario apart from a game like L.A Noire, would be the increased freedom of choice. Unlike a 1940's detective, a sheriff in the Old West is allowed plenty of liberties within the law. Outlaws can be dealt with in whatever way the sheriff sees fit. There aren't many questions of morality, and doing things 'by the book' isn't exactly a necessity.
This would allow players to choose what kind of officer they want to be: good-natured, or just someone who does as they please.
Since Redemption was more about the theme of the dying Old West, perhaps this could allow for a theme of combating corruption in a world that only seems to reward the non-innocent. It would allow the 'Wanted' side missions to make a comeback AND it would open the door for some co-op play in which multiple players and their personal law enforcers can take down assorted gang hideouts. A realistic interpretation of a modern-day officer would be enjoyable, but being a sheriff in the Old West would offer up even more wild possibilities.