A New Hope, The Empire Strikes Back and Return of the Jedi all look pristine on Disney+, based on my time with a demo setup. The image looks sharp and detailed, with no ugly edge enhancement and a healthy dose of film grain. The original trilogy certainly won't be a showcase for Dolby Vision HDR like The Last Jedi, but in the few scenes I glanced it, the technology allowed gave the image a bit more depth and nuance. And while I didn't get a chance to check out the immersive Dolby Atmos upgrade, I'm looking forward to some lengthy testing my home theater.
Dolby and Disney reps didn't have many specific details to share about the Star Wars remaster, but that doesn't make it any less significant. The first two trilogies hit Blu-ray back in 2011, so it's been a while since they've been retouched. And while there have been rumors about a 4K boxset, that likely won't arrive until 2020. For now, Disney+ is your only source for 4K Star Wars.