I know this would probably be something that most people would say no to, but I think it’d be really cool to have a scene of Vader wiping out Jedi in a duel as a new extended intro for A New Hope. It would be a fierce duel against multiple remaining Jedi that have all come out of hiding and teamed up in coordination with the Rebel Alliance as a distraction from the Battle of Scarif so that Vader is occupied during the battle to increase the Rebels chances of successfully retrieving the plans. The odds would be way against him but he of course would prevail due to his sheer skill and strength (being the most powerful force user at the time of course), before being notified about the Battle of Scarif. So we see what he was doing between his meeting with Krennic and his arrival at the Battle of Scarif. Maybe he gets his chest plate damaged so after the duel he temporarily swaps it with an inferior smaller one until he gets a new one, which is why his chest plate is different in ANH from the rest of the saga. I think it’d work as a way of showcasing how much of a powerful juggernaut Vader is, thereby making him more terrifying and threatening overall in the OT, and so all of Vader’s best feats aren’t just from the comics and other supplemental material. Plus IMO more lightsaber duels in the OT wouldn’t be a bad thing. I think it’d be awesome and no harm done, especially if its just an alternate version.
It’s something I’d love to do as an alternate version of my ANH fan-edit. As for how to actually make it, basically my thought would be using footage from fan-films a lot like daneditor did with his ROTJ radical edit. Episode 2 of Star Wars Theory’s Vader fan-film looks promising; Mace Windu could just be edited to be another Jedi by changing his lightsaber color, and there’s also going to be other Jedi aiding him in the fan-film (the concept art looks really awesome), and I’m sure we’ll see them duel Vader. I could just take clips from the duel(s) and compile them together to be coherent. I mean, the thing isn’t out yet so there really isn’t any way to predict exactly what it’ll be like but from what I know right now I could see it as a definite possibility.