I don’t know that a deepfake would actually help because the problem with that scene is the way the mouth moves. Anything you deepfake over the underlying motion is going to have the same motion, isn’t it?

You’d have to basically just head-replace their head replacement.

Honestly, a fan-edit of Rogue One that really wanted to treat Leia properly and in the context of A New Hope following right after would KEEP HER HIDDEN entirely, and never show her beyond that one glimpse from the back. There was a reason Lucas waited to reveal who she was until so far into Star Wars. Having the Leia of that movie, the angry, rebellious, “lets get the mission finished first, whatever it takes” Leia, be revealed at the very end of Rogue One as a not-great special effect, all wet-eyed and smiling while talking about “hope” just doesn’t mesh at all, really.