I think the general principle behind feeds was always content discovery rather than loyalty to a particular author. Blogs were so effective because the likes of Coding Horror didn't just post some insight into programming but generally linked to lots of other really interesting posts that could educate and entertain for as much time as you had to burn. The only problem was if you wanted to do this every day, then it was hit and miss and your reading list for the day was too dependent on a good writer having something to say when you wanted entertained (hence the volume of my subscriptions).
Aggregation sites like Reddit and Digg were the next stage in content discovery but the noise ratio was far too high to replace my RSS feeds. Then the niche sites like Proggit and Hacker News pretty much eliminated my need for RSS. Whereas previously I could spend an hour reading my personal feeds and come away feeling like I wasted an hour, now I feel like an hour on HN will not only keep me aware of the emerging trends in my profession but also give me lots of interesting anecdotes from the general interest articles that are posted here. It's an invaluable source of information.
Content discovery is a really exciting space, and I'm really excited to see how it will evolve. Twitter is another evolution of this I think, and I think way more people use twitter as content discovery or a news source as opposed to "what I am doing right now." But following one of these loudmouths who retweets and links to articles suffers the same problems as RSS in that there is this tendency for one of these people to make a huge amount of tweets due to some event like a conference (or gets drunk one night) and then some stuff you don't care about pushes a lot of the stuff you do care about off your page. I only follow 25 people on twitter and if I don't check it for a day then I have 200+ tweets to dig through, so I have no idea how people with massive lists make their twitter work for them.
The general problem from all existing solutions I see is that they are too immediate. Aggregation sites work on a day to day basis where time of upvote plays more part than overall quality. Twitter goes out of its way to make anything other than your latest tweets hard to access. And right there at the side you find emerging trends. It's all about now, now, now. But generally I find information on the here and now pretty easy to solve, it's those timeless classics that appeared on HN front page eighteen months ago or were retweeted by 100 developers last week when I was on vacation that I want to be able to always have access to. Especially on the days where the whole HN front page is dominated by some topic that I find mundane (Joe Blogger's latest opinion on the iPad!).
I hope the next big iteration in content discovery will try to solve that problem.