By retribution, did you mean 'redemption'?
I strongly hope that he doesn't die. For him, that's too easy a way out and it lets him escape having to deal with the choices he's made. For us, it's too familiar and bloodthirsty a pattern, and it makes this a trilogy kind of about "the fall and death of Ben Solo". Seriously, why is it that even in most children's movies, we have this motif of the evil villain getting what they deserve by *being killed*? Even when we want to avoid the Hero doing this (because they're Batman/Simba/a Jedi/etc), the villain's death by conveniently non-Hero means during the final confrontation is an all-too-familiar trope. I don't see the point to it.
I like the idea of Kylo being an analogy for a heinous criminal in society. All of them were at one point kids with bright prospects, but somewhere along the way they went too far down the other road. Society (particularly Leia, and Rey) can't forgive him, but neither (I hope) would they be seeking the death penalty to fulfill their vengeful needs. He'd have to be defeated and rendered powerless in some way, and perhaps in that state we'll see him, Leia, and Rey come to terms with what he's done - especially to Han.
I'm a big fan of
Avatar: The Last Airbender and there's some parallels here between benders and force users. One ability reserved for the supreme bender (the Avatar) is that of taking away another's bending power, reserved for the most extreme of circumstances. So that's what I'd like to see here. If Rey gains this ability and, after many chances, decides to use it to sever Kylo's ties to the Force for good, it will both be his defeat and the culmination of her rise as a true Master. She doesn't become a killer even incidentally, but she *does* make a conscious choice to destroy her opponent in a way that he does deserve. From there, Kylo's life failings can be explored. He may hardly have time to come all the way back at the end of one movie, but there'd be a glimmer of hope that he, Rey, and Leia can reconcile some of the things that have happened and he'll end up, I don't know, writing letters to Rey in the future from his prison cell (a Lawrence Phillips/Tom Osborne analogy here, to be recent
)
In general, I'm not a fan of employing the Plot Twist (as reveals such as the Han/Kylo collusion theory or the Plageuis theory would be). The
OT has one of the most memorable ones in cinematic history. There's no way it can be attempted again and land with the same impact. And it's not like a movie epic needs one; this is neither
The Sixth Sense nor a daytime soap. At some point in the future the entire plot of the films will be known, and I'd hope that would only mean "Hey, I want to see how the told story!" versus "I guess I know the big secret the entire thing was leading up to! At least we have our own generation's version of Darth Vader memes."
