I'm amazed people think there's some copy of Kirk that could pop out of the Nexus anytime it wants. Guinan was pretty clear about that. Explicit in fact. She could not come out because she already was out. She said "I can't come with you, I'm already there". Why would Kirk be any different. Guinan has the unusual 6th sense about things. She knows what she's talking about.
There are basically only two ways to do it. One is you contradict it and pretend it never happened. I wouldn't put money on that ever happening. The other is Shatner plays an older version of an alternate Kirk, like Pine's Kirk. That's doable.
Honestly, I have a feeling people would be sadly disappointed. I just saw Shatner last night. A local theater was running TWOK on the big screen and Shatner came out after to talk to the audience. No disrespect to Shatner, I really mean that, but he's out of shape and like a lot of people in their 80s he was hesitant. It actually bothered me a bit. I've never seen Shatner like this. Whenever I've seen him in the past on interviews and speeches he was sure of himself and while he's gotten a bit on the heavy side over the years (like many of us) he carried it well enough. Now, he's still funny and charming. And his personality's still there. But he left Captain Kirk behind a long time ago and I personally prefer to remember Shatner as Kirk in his prime, like TWOK. And Shatner himself says when it comes to his career he prefers to live in the moment. He's enjoying what he's doing and I got the impression he's said good bye to Kirk some time ago.
I did enjoy him talking about his friendships with Nimoy and Kelley. He didn't talk about any other cast members. But he considered both, and Nimoy in particular, to be the brother he never had (which he said as much) And that might be another reason he probably wouldn't play Kirk again, it wouldn't be the same without Nimoy.
He did take a bit of a veiled swipe at the Abrams movies. He noted how in order to profit off a movie a studio usually needs to make more than 3 times it's cost to make. The first 6 movies just made that more or less. Then they moved on to the Next Generation movies he said and it was sort of the same thing. Then the Abrams movies came along, became more like Star Wars and Paramount got what they wanted. All fine, but the swipe was that he said they sacrificed the emotional impact that Star Trek had previously. He didn't elaborate beyond that.
Another amusing moment was when a question from the audience was what was his favorite Star Trek movie. He jokingly said, well 5 he heard was a pretty good movie (he did briefly admit that movie had a lot of problems but then moved on). That got a laugh from the audience. He was coy about questions like that though. He wouldn't say what his favorite was personally.
