Attorney here.

The original version of A New Hope should enter the public domain in 2072.

The Special Edition of A New Hope should enter the public domain in 2092.

The despecialized edition uses work from the special edition and would not be legally distributable until at least 2092. But as to your question on resolution, I do not believe copyright law would differentiate between a work bases solely on the published resolution. As the other comment suggests, A high res scan of the original A New Hope, if it exists, would be in the public domain in 2072.

Kinda weird that I was born about a decade after the release of that movie and have a very good chance of being dead before it goes into public domain. Seems ridiculous.

There is another fan project called "4K77", which also attempts to restore the original version of Star Wars. They somehow managed to get their hands on the original film reels, and scanned them digitally in 4K. It looks very grainy, but this is to preserve the original experience of watching the film in theaters in 1977.

So if you want a modern-looking and cleaned-up version of the original "New Hope", then watch Harmy's Despecialized Edition (keep in mind it's only 720p). If you want the genuine '70s theater experience with the film grain and everything, watch 4K77.

The despecialized edition uses a ton of cleaned up shots that don't change in a story sense but have grain and wires and other compositing errors cleaned up. These are new works. Even the VHS release and any HD releases could be considered new works as the colour and sound would have been tweaked for each format. The best thing to do would be to find an original film print and have it scanned. Anything else would push the clock back.

The way things work with Sherlock Holmes, some of the original novels are in the public domain (because they were written before the cutoff) and and others are not (because they were written after the cutoff.)

Sherlock himself is in the public domain. And he plays the violin. That's also in the public domain. But he didn't get a dog until a later book, so that's still under copyright. And he didn't get a diagnosis of bipolar/manic depression until later, so that's also under copyright.

So if you want to write a book about Sherlock, that's fine just as long as you don't give him a dog or bipolar or otherwise use any elements from after the cutoff.

So, I believe the original trilogy will be in the public domain in 2073 and later additions (Han shooting second, musical numbers added to the special edition, etc) won't be in the public domain until later.

If the "Despecialized Edition" was made from the 4K version, I think it's certain that the elements added after the original trilogy's release would be remain under copyright for a time after 2073. But if there are any scenes that are straight up one-to-one identical between the original release and the 4K edition, I'd guess whether those would be under copyright after 2073 would depend on whether restoration and/or upscaling qualifies as sufficiently "creative" to warrant it being a distinct copyrightable work from the original release version.

Now, even just the act of making copies of parts/all of either the original or 4K endition (in the process of making the Despecialized Edition) probably qualifes as copyright infringement. So those folks definitely would be in trouble if Disney went after them. But after 2073, whether trading copies of the Despecialized Edition will be illegal will depend on whether upscaling and restoring qualifies it for fresh copyright, and also whether any copyrightable creative elements from after the original release are included in the Despecialized Edition.

Sorry. That's a lot of words just to say "I dunno." But I think it's fair to say that after 2073 if someone upscaled the original theatrical version from that DVD release that had it (assuming nothing new was added to that not in the original theatrical release), it'd be perfectly legal to create and trade copies of.

A long time ago I got rhe trilogy, but with the crappy cheezy 3D stuff added I went on a hunt for the "originals", nice to know why I didn't find them!