From what I understood, the whole Blu-Ray/HD-DVD thing was to provide movies in high definition. Obviously this technology is still expensive as Hi-Def televisions are still expensive. And it isn't just an HD TV you need to view HD (or so I've heard). They NEED the extra storage space to provide the higher quality video.
As for consumer data storage, as with all technologies, the discs will be expensive at first until production costs have been reduced and prices not just for discs, but recorders/burners are available to a larger majority of people. I don't have any statistics, but I think that the average consumer still thinks that DVD-RW drives are still prohibitively expensive or are just barely getting used to the idea that they aren't. Even still, Dual layer DVDs are kind of expensive. I spent about $15 for just 3 DVD DLs only a few months ago. Yet most movies and sometimes even the bonus discs that come with them are dual layer.
I would love to have a bunch of Dual-Layer DVDs but they're too much money for me right now. I backed up my relatively small mp3 collection about two years ago and it took me 11 CDs. My music collection has grown since then and I thought it would be nice to fit it all onto a few DVDs, But what would be even better would be to fit it all onto one DVD DL. And even DVDs have different, confusing formats. There's DVD+R or DVD-R.
Aside from all that, I heard a few months ago that physical media is going the way of vinyl records. Right now I say "Yeah right" to that but at that same time I heard about another format in the works. Holographic storage
. These discs can hold almost 4 TB of data.
a 3.9 TB HVD could hold between 4,600–11,900 hours of video—just over one year of uninterrupted video at usual encoding rates. [Emphasis Added]
My memory is a bit hazy on this but I think they said that the technology should be widely available by 2010.
So, when it comes to entertainment media, HD-DVD and Blu-Ray will make a difference, and Sony, who claim they made DVD broadly accepted because of their PlayStation 2 system, are trying to push their Blu-Ray format with the new PlayStation 3 system which sells for a ridiculous $700 later this year.
When it comes to consumer data storage, I'd probably be fine with DVDs--Dual-Layer or not--until HVD becomes more widely available.