I keep hearing whispers in the rumor mill about a new one but nothing official. When they did that remaster/update thing for GTA and they were showing environments, I originally thought they were announcing the next RDR. But of course, that was for GTA.
Given RDR's commercial success I know they will make another one (it would be ridiculous to not ride that money train longer if they could). Question is mostly when, and if they ever give up this GTA bs. Or at least take a break from it for a bit. There's only so many hookers you can beat up, right? (Right? *worries*)
Given that, I'm also surprised that there aren't more western-themed games out there. I get the allure of magic in Final Fantasy, and shooting bad guys in CoD, and the complexities of space and choice making in Mass Effect. But I find it hard to believe that the gritty, tough world of America at the turn of the century has no inspiration for game makers. (Well, obviously this is a broad statement, I know of a few western-styled games but I digress.)