Challenges of RSS are significant however, though whether it is really important or not, I'm not sure. For one, it takes the focus away from the site and many businesses/bogs/etc. still think it a rather silo-like matter, mostly influenced by advertisers who just want easily measurable clicks. I'm sure that can be overcome however, the question is whether people are ready to accept hybrids between the open infrastructure of RSS and the closed one of the URL. Since it's arrival, it has yet to be mastered.

What else… feedreaders. You're right, Twitter, Facebook, etc. have revolutionised/replaced feed readers in many ways, which doesn't make RSS dead, just the reader and by default perhaps our association between the two. It's still far more efficient to read news through a reader than it is via individual websites. Perhaps that is even surpassed by the social feed reader, aka social networks, but I'm somewhat skeptical.

RSS: an interesting technology with huge potential, but only monetisable/usable if integrated well with content and consumption.