Here's how I've heard things. The next real release (in between this cycle and the next) is Core 2.0. From what I hear, FFG doesn't want to actually announce Core 2.0 until as late as possible, because of what that news will mean for game stores. Right now, game stores sell the most of their Netrunner product as the Core sets from new people trying out the game. If a Core 2.0 is announced, it devalues the crap out of the original Core set, since at that point it's no longer really a valid product. This means that all the Core sets that stores have (and what they're ordering the most of, since it's what sells the most) suddenly become nearly worthless, and have to be replaced with Core 2.0 sets. Supposedly, we'll hear about the next Core around Gencon.
As far as the next set goes, it's being partially redesigned by Boggs, as apparently it needed it. So that's one reason it hasn't been announced, as cards are (or at least were? I don't know how extensive this was or if it's done or not) being reworked. Another reason is that this set is mostly designed around making up for cards that Core 2.0 and the upcoming rotation removes from the game. They're not strait up re-printing cards that are removed, nor are all the cards similar ideas from what's being removed, but the printing similar concepts of cards that do exist might raise some eyebrows if they announced them right now, since people would be like "Wait, doesn't that effect already more or less exist in X card?" without the knowledge that X card is going away.
Anyhow, that's the scuttlebutt. Normally I take things like this with enormous chunks of salt, but I've heard this from enough different and trustworthy sources that at this point I'd have to be actively dissuaded from the veracity of them.
The Net isn't falling, it's just being redesigned