Assuming copyright laws don’t change by then, otherwise there is no way to know.
A plausible answer is 1977 (when the film was released as Star Wars) + 95 years (for pre-1978 works) = after 2072. However, the film had been edited by George Lucas for the 1997 “Special Edition” release. Does this mean that I cannot publicly play the Special Edition VHS tape I have at home in 2073 and have to wait until 2093, or perhaps 70 years after GL’s death?
George Lucas has been infamously attempting to erase copies of the original movie. Therefore, no HD home video release for the 1977 film exists, however, a fan effort known as the “Despecialized Edition” compiled different versions of the movie from various sources, patching the Special Edition 4K Blu-ray rip to try to replicate the original 1977 experience. Does this legally questionable version enter public domain in 2072, or does this only apply to official (SD) releases?
Anyway, the Despecialized Edition project as well as George Lucas’s treatment of the originals is an interesting rabbit hole to delve into for any movie nerd.
First sentence of my post, for this very reason – they own the franchise, after all. The law may also change the other way but that’s very unlikely to happen in the US within 50 years.
I wonder if they could develop a system of draconian DRM (only their own theatres with metal detectors, personalized online streams…) and mildly edit movies every few decades so that they can destroy the original and effectively renew copyright. The gaming industry’s always-online DRM makes nuking a release possible but copyright lasts for about 20 console generations (we’ve only had 8 so far!) so they don’t even have to do that.