So many people are missing the point with Blu-Ray...
The Blu-ray disc can store 25 GB's of data, a dual layered disc can hold twice that. This is vastly greater than a standard definition disc. Six and half and ten and a half times respectivley.
This allows space for high-definition video and high-definition sound.
The former has been mentioned already this thread and to those who say there is no difference, you are simply wrong, or blind, or in a varying state of blindness.
Even if that were the case, it is the high quality audio which does it for me. And you, unless you are deaf, or in a varying sta-
Anyway,
As no-one has even brought it up, I... *googles*... will allow would have allowed someone else to describe the benefits of HD audio but I couldn't bloody find anything.
So I'll proceed to talk out of my arse a little longer...
An HD audio track is basically an uncompressed audio file (remember MP3's and how shit a low quality one sounded?). With a Blu-ray source and AV equipment capable of playing said audio files, you will achieve enlightenment HD audio. Since I failed to provide any technical data on what that means you'll just have to take it from me that that is true. (no wait don't scroll down, i'm not done yet)
Uncompressed audio is a good thing because it allows for crystal, and I mean crystal clear audio. If you happen to have a decent audio set up, this is a good, good thing.
I noticed it most with Kung Foo Panda. There was a scene where a ceramic bowl was balancing on a table, spinning around before coming to a halt (you know the sound I mean). It actually could have sworn it was in the room with me. If you watch action films such as Iron Man and The Dark Knight you will notice every damn gunshot, every line of speech, every footprint sounds like it is in the room with you.
Blu-ray is without question, an experience and I sense too many people are judging it without fully experiencing it's awesomeness.
-On topic
If the BD + DVD discs are true, then yes it will take over conventional DVD's
If not? I don't really care either way as I already have Blu-ray and If something else even better comes along, I'll be all over it like a fly on shit.