Reddit is Fun will shut down on June 30th in response to Reddit API changes
One thing I've been a little surprised by is the idea that, even if the API pricing was reasonable and these apps weren't shutting down, that they wouldn't be heavily and severely impacted by the fact that 3rd party apps will not be able to access NSFW content.  Reddit has a LOT of porn on it.  Preventing 3rd party apps from accessing that content is a pretty good indicator to me that they're going to completely get rid of that content, eventually.  People keep making Digg references, but I'm not sure the real answer won't actually be Tumblr.