When the new series of Star Trek movies introduced a new timeline and new characters, it did so with the help of our old friend Mr. Spock. Ever since then, there have been rumors about trying to get the original Captain Kirk into the films as well. Everybody seems at least be somewhat interested in doing this if they can make it work, but they've never pulled the trigger. As it turns out, there's a very simple reason for this: it's difficult to bring William Shatner's Captain Kirk back because he's dead.
We apologize for the minor spoiler if you're not caught up on all your old Star Trek movies, but way back in 1994 in Star Trek: Generations, the film that put the original series and Star Trek: The Next Generation crew on screen together, James T. Kirk was killed by Dr. Tolian Soran as he helped Jean-Luc Picard prevent a galaxy destroying event. Star Trek producer J.J. Abrams tells IGN that while he's not against some sort of a story that would overcome this minor issue, he has yet to hear an idea that would really work.
Obviously it's Star Trek, nearly anything is possible. There's the fairly simple notion that on the day Kirk was born another timeline began. But in the other timeline, Kirk died onscreen (in Generations). I don't know how he would come back unless we went into this other reality and we did a timeline and reality jump.... In all the years we've been working on this, I've yet to hear a pitch that didn't sound too contorted and contrived for an audience to swallow. And I've talked to him (Shatner) about it. If Kirk had lived there'd be an answer. But there's something about his having died that makes it impossible.
As plot difficulties go, death is certainly a problem. One of the reasons that the new Star Trek movies are embraced by fans is because it went through the effort of giving us new stories with the original Enterprise crew, while telling fans that all of the previous Star Trek stories still happened in the original timeline. Spock's time traveling doesn't take place until everything in the old Star Trek shows and movies has already happened. To go back and meet Kirk before he died would impact that old timeline. The character of Kirk was brought back to life in subsequent Star Trek novels but...yeah. Even if that was a good idea, it still impacts the original Star Trek timeline- unless you have Kirk's resurrection happen as a separate event and don't have him cross paths with the new timeline for about two decades or so. See how this is getting convoluted? Yeah, that's the problem.
William Shatner has always said he's up for returning in the new films, so perhaps at some point there will be an idea that works. The implication for the already announced Star Trek 4 is that time travel will be involved, so who knows? As J.J. Abrams says, this is Star Trek, anything is possible. Star Trek Beyond opens Friday.