WARNING: If you haven’t seen Rogue One yet, this article will contain spoilers as it discusses how the ending changed.
i09 found a podcast interview with Gareth Edwards on Empire’s website that has since been removed, and he describes that the original scripted ending for Rogue One was very different than what ended up in the final version in that not all of the Rogue One team died:
The very first version, they didn’t. In the screenplay. And it was just assumed by us that we couldn’t do that. ‘They’re not going to let us do that.’ So I was trying to figure out how this ends where that doesn’t happen. And then everyone read that and there was this feeling of like, ‘They’ve got to die, right?’ And everyone was like, ‘Yeah, can we?’
We thought we weren’t going to be allowed to but Kathy [Kennedy, President of Lucasfilm] and everyone at Disney were like ‘Yeah it makes sense/ I guess they have to because they’re not in A New Hope.’ And so from that point on we had the license.
I kept waiting for someone to go, ‘You know what? Could we just film an extra scene where we see Jyn and Cassian, they’re okay and they’re on another planet?’ And it never came. No one ever gave us that note, so we got to do it.
This likely explains why there were so many different shots in the first two teaser trailers that didn’t end up in either the final trailer or the finished film. There are a lot of shots on Scarif of the Rogue One team, including shots of Jyn holding the data tapes while running on the beach, which aren’t in the film.
It’s very possible those are filmed scenes from the version where most of them survive stealing the plans. That’s also probably why Felicity Jones had a sequel clause in her contract, which was widely reported this past week.