Is there any evidence that blogs are dropping RSS? I think one of RSS's major applications was for blogs to distribute their content. The examples given in this article, such as Twitter and Facebook are both apps that also have APIs available, so RSS in those cases are kind of redundant.
One could also make the argument that RSS is bad for the bottom line, as selling advertising, and generating revenue off of it is far more difficult than traditional websites.
The other big question is whether or not users are still using aggregators. If aggregator use is down, then that could suggest the decline of RSS or RSS like technology.
Finally, RSS probably still has a future in podcasting.
I can't just import their API into an RSS reader with a single click.
On the other hand: I probably could, if I spent a few days reading up the documentation, writing up an app, testing it, and then deploying and hosting it, resulting in an RSS feed that (e.g.) Google Reader could process.
My fiance? No way.
On the gripping hand, my fiance doesn't care about RSS and doesn't use it. I'd argue that most twitter users probably don't, either. So there doesn't seem to be much loss.
And services like Flipboard benefit having access restricted to an API, as it limits its availability, which helps them monetize off of it.
For example, I follow the BikeEXIF blog (http://www.bikeexif.com/) via his Twitter feed on Flipboard. This feed includes all of the blog posts, plus links to other 3rd party content, commentary, and so on. This is much more interesting than a pure RSS feed.
RSS may not be as useful to real humans, but I do think it's tremendously important and very much alive as a service to service standard. I wrote the RSS ingestion system for Flipboard. When reading the BikeEXIF blog on Fliboard via the @bikeEXIF Twitter stream, the content of each article is fetched from the blog's RSS feed.