Scoble explains in a Wired interview why RSS will remain important - but will also stay niche:

In an RSS aggregator it shows you any new things, so it makes it so much more productive. So the first thing I ask is, do you read more than a couple of sites? Do you keep going back to the same sites?

And that's why it's not going to go mainstream, because if you're reading only one or two, there's not enough of a productivity gain for you to care.

That's why journalists and newsfreaks care, people who are passionate about keeping up with lots of things. It's the passionate ones, and they're the ones getting everybody to pay attention anyway.

That's about the size of it. People like me (I'm subscribed to 311 feeds right now) are outliers - most people just aren't interested in that much news and information. If you visit a handful of sites once or twice a day, a browser works great, and bookmarks are sufficient. It's only when you start trying to follow tens (or, like me, hundreds) of news sources a day that an aggregator becomes critical.