User blog comment:ZERO N7/Any plans for more DLC in 2011?/@comment-1265875-20101130184647

I think they're going to be concentrating more on L.A. Noire than they will on more RDR DLC, unfortunately.

But you never can tell, Borderlands had a new DLC last month and it came out in October 2009. So maybe closer to the 1-year mark for RDR, they might come up with something else.