In my opinion, dvd sales were somewhat of a fad, that being somewhat of a misnomer. Before dvd, watching movies wasn't as easy as everyone thinks. Only major releases on vhs were affordable, and prices of vcr's weren't the same as the cheap dvd players that followed. Ten years ago, cheap dvd players cost $30 dollars. Walmart had (and still does) bargain bins of $5 dvds. People bought them by the buttload, because it was cheap. Shit, half the dvds purchased by your average consumer were probably watched once then put on the shelf. People aren't going to buy crappy movies twice when the first time they bought it, it was $5 and now its $15 on blu-ray, but they might pick up Gravity or something similiar that they'll watch more often. I still see a market for 4K physical media, but it;s not going to be like dvd, as it should be.