A ton of movies were reissued on Blu-ray, re-scanned from film. DVD has garbage resolution and compression, while film is made to be projected on gigantic theater canvas. Surely you don't believe movie theaters were effectively displaying 720x480 or 720x576 at the size of canvas?
Personally I find that even BD-rips made in SD resolution look better than DVD—if only for contrast enhancements made for reissues, and due to better compression formats.
Moreover, if the source was shot on 70mm film then people might still keep re-digitizing it in the 22nd century into fresh HD formats of the day.
Consult this video, for example: https://youtu.be/sCv-dIFGcd0
Personally I find that even BD-rips made in SD resolution look better than DVD—if only for contrast enhancements made for reissues, and due to better compression formats.
Moreover, if the source was shot on 70mm film then people might still keep re-digitizing it in the 22nd century into fresh HD formats of the day.