The Los Angeles Times recently sat down with Star Trek 2 writers Roberto Orci and Alex Kurtzman, who revealed that they have 'broken' the story for the sequel. According to them, it will not be the second act of a trilogy, but a stand-alone story.
Roberto Orci had this to say in terms of Star Trek 2 not being part of a planned trilogy:
"I don't know that we've ever thought of it in terms of a trilogy. We thought of the first one as, "How do we tell how this happened the first time and how do we free it so that it can go on forever without stepping on what came before." So, if you were thinking of this movie as a second act, yeah, you would think of it as an "The Empire Strikes Back" sort of story, but I'm not sure we're thinking of it as a second act. One of the big challenges is all of the characters are together now. A prequel is a pain in the butt, but one of the nice little advantages was that you get to meet the characters as you go through the story and they get to meet each other. We don't that luxury of not having the entire family there together at the start of the story. So now you want the character stories to be good for everybody but also not just be there to be stories but also fit into the plot and be organic. We're looking at a lot of the old episodes for inspiration, still. Whereas the last movie was all about breaking free from "Star Trek" and its canon, now that we can do whatever we want, we still want it to feel like good ol' "Star Trek" even though it's a new story."
Alex Kurtzman continued by offering this:
"We have broken the story, which is very exciting. I think one of the weird challenges that we're facing on this one is that in many ways, with the first movie, I don't think people knew what to expect, so when we were in the writing process, (we) really spent our time going to things that we loved about "Trek" and it was a very unfiltered process. It felt intimate and small. We need to find our way back to the same kind of vibe that we had when we wrote the first one: What do we want to see here? What moved us about "Trek"? Where can we go from where we left off?"