This is exactly why physical media is so important. I redeem all of my digital copies and over the years many of them have "disappeared" from my accounts because when the studio loses the rights to the movie (it sometimes happen if they shared production costs), the movie you purchased is no longer "yours." For example, if Paramount and Warner participated on a movie together and Paramount owns the home video rights for 20 years and then they revert to Warner, if you purchased (or redeemed a digital copy of the Paramount film) it will be taken from your digital locker since Paramount "sold" it to you and no longer owns the rights. Frankly, I consider this to be theft!
David, you are so right. Also, some movies and TV shows just disappear for reasons not released. In fact, there were movies and such they were on videotape that never made it to video discs. In another example is that I have a version of Star Wars on laser disk that never made it to DVD. In my version, Harrison Ford shoots first. And many interviews on discs that were bonus. Features will be lost forever.