Before DVD's arrived, most people thought it was WEIRD to own a physical copy of a movie.
After all, the vast majority of people do not watch the vast majority of movies more than once. Only the most dedicated of nerds and cinemaphiles maintained large libraries of VHS tapes and/or Laser Disks.
DVD's became cheap enough that people started to feel that they "might as well" go ahead in buy them, especially when $35 at Best Buy allowed you the opportunity to watch stuff like all the episodes of Season 2 of "Buffy the Vampire Slayer" in sequence. But that only recently has been how the market has behaved, and if streaming continues to get better and cheaper, I can see people not caring about owning disks anymore.
Heck, I used to line a wall with disks just like every other movie/TV junkie... but I don't believe I've purchased a new DVD since Spiderman 3, and now I'm wondering why I bothered.
If I want to watch a new release, I can add it to my NetFlix queue and wait a couple days with pretty much no cost beyond what I'm already paying for the service, or I suppose I could shell out a couple bucks to "rent" it off iTunes if I'm in some kind of a hurry. For most old movies (and a growing library of TV shows), I can stream them immediately off NetFlix and/or Hulu.
So it's unlikely that I'll buy another DVD ever, and buying a player for a new format is out of the question.