In the below video interview with two developers from Insomniac Games talk about creating Ratchet & Clank Future: Tools of Destruction. In the interview they are asked about things they had to cut from the game, which gives some interesting hints at Ratchet & Clank Future 2 about 2:30 minutes in.

To quote the answer: “There were certain things in the story, characters that I wanted to address more in this part of the story arch that we’re not going to address until a later part of the story arch. So I can’t go into too much of who they were. … For instance the Max Apogee [the Lombax Anthropologist] story arch is something that we were not going into too deep, but we hint at it. And more of the background with the Lombaxes and what happened to them. It’s things we hint at. The Zonie and the history of the Zonian and who they are. There’s a lot of background to the world. If you interact with a lot of the NPC characters, you’ll find out a lot of hints about it.”