I'm toying with building a site that would aid people who use RSS entirely for things that they scan through but don't need to read (nor care if they miss parts of) in transitioning from RSS.
The notion is that every site (exclusive of personal blogs, really) that has an RSS feed that updates regularly almost certainly also has a Twitter feed, potentially an App.net feed, or a mailing list, or some combination. Email lists stink for frequently delivered routine stuff, but many of the RSS feeds I follow, I'd be better off getting a monthly newsletter than daily headlines.
While I have problems with Twitter having clamped down on behavior that software clients from third parties can engage in, it's still very useful and there are many Twitter accounts that are effectively the same as the RSS feed. (The difference is really the preview, but I mostly scan headlines in RSS. Some Twitter clients did — do any still? — let you see a Web preview of anything included in the message.)
App.net isn't yet of a scale to replace RSS or Twitter feeds, but it added a free-by-invite tier perfect for announcement accounts, since the free accounts may have unlimited followers (but only follow up to 40 others). App.net allows robust use of its API for interaction, and thus I wouldn't be surprised if sites gear up for the slight expense or trouble of paying $100 per year for an App.net developer account and pushing out one or more RSS-like feeds there.
If I built a site, I would let people add mappings: Web site name, feed name, sub-site URL (main site if not a subsite), feed URL, Twitter account equivalent, App.net account equivalent, and a URL pointing to a mailing list. Then people could upload OPML files or lists of feeds and this site would spit out the equivalents. Needs to be crowdsourced, although it's possible I could write a scraper that would pull down some of the information itself. I'm not sure I have the chops or time to do this at the moment, as it requires a decent form front end to update data. (The back end, I'm solid on.) I'd also require moderation, so that people couldn't just post nonsense or overwrite good information with new, bad information. Thinking on this.