Unclear. Shuhei Yoshida said that "hiatus" is a misleading word that Jack Tretton used and that all it meant was that they are not releasing new information. When further questioned he said he can't talk about the platform for Last Guardian. As you can see below, he also mentioned that the team is "re-engineering" the game and due to this the team size is smaller. What does that mean?
Q: I'll wrap up with an inevitable question which you're probably not going to answer. The Last Guardian - where is it? It's in this building [Sony Studios Japan] somewhere, presumably?
Shuhei Yoshida: Yeah, in this building!
Q: What console is it coming out on?
Shuhei Yoshida: Ahh... That, I cannot talk about.
Q: It doesn't seem to make any sense for it to a PS3 title so late in the lifespan. I know they have PS4 kits in their office, because I heard them talking about them...
Shuhei Yoshida: So, we're waiting for the right time to re-introduce The Last Guardian in an appropriate way. I can't... Well, the game is in development, and it's well staffed, and Ueda-san is here, working - even though he's not a Sony employee, he's dedicated to the product. But we're not ready to update yet.
Q: The hiatus that was talked about at one time, that's over now? It's back in full production?
Shuhei Yoshida: Hiatus, I never... It was Jack Tretton! He used that term, and I said no, hiatus is misleading. It was a hiatus in terms of releasing new information. The game has never stopped - the team has always been here. They're going through the re-engineering of the game, so the team size is smaller, because it's more engineering focused right now.