Not sure if this is being discussed elsewhere, but…
Theory: the original ending to Rogue One was changed in post-production, away from one where Jyn and Cassian at the least might have survived.
Evidence? The trailers. Having footage from movie trailers not make it into the final product is not an unusual thing; they are made and released during post, and sometimes footage is cut or different takes are used. Rogue One is no exception. The best examples of this are Jyn’s initial meeting with Mon Mothma, Draven, and Cassian (almost none of the dialogue from the first teaser trailer is in the film, i.e. “I rebel”) and Saw Gerrera’s entire “what will you do” speech. But what interests me the most is some action footage.
First, there’s a shot of Jyn and Cassian in the cockpit of a spacecraft, an orange sunset glowing outside. (”Good?” “Good.”). Then there’s a shot of Krennic walking through the shallows of the beach on Scarif, also at sunset, headed towards some flaming wreckage. But most telling for me is this shot of Jyn, Cassian, and K-2S0 running through the tower on Scarif with the data drive containing the Death Star plans, along with footage from the Celebration sizzle reel showing Jyn and Cassian running on the beach still with the data drive (there’s another shot of this in the original teaser trailer too). There’s even footage of Alan Tudyk running on the beach in his motion-capture suit. Finally, there’s the shot of Jyn limping toward the edge of the tower deck, which in the film did not include a TIE Fighter rising up to meet her.
So, all of that together. We know from the film that the data drive never left the tower, so why is there footage of them running on the beach with it, or even through the base itself? Jyn went straight to the top of the tower after acquiring the drive. My only conclusion is that the decision was made to change at least part of the ending. We know they did some reshoots. Perhaps that cockpit shot was Jyn and Cassian leaving Scarif. (Who the hell knows what Krennic was getting up to in his own beach shot, I just know he never got anywhere near it in the final film.)
I just can’t help but be curious as to what the original ending was, if anyone actually survived, and why it was changed. Interested to see if any of this makes it onto the Blu-ray.