You are not alone with this assumption. George Lucas has been saying it for quite some time now: optical media will be replaced by downloads. And Microsoft seems to think along the same lines. If you have watched the HD Rant thread and some of the threads over at AVS it becomes pretty clear that M$ is not in it for HD-DVD but mainly for VC1 and how much compression can they get away with.
Personally I don't think blu-ray will be that much of a niche product. Look at how many discs of CR have been sold in the first 2 weeks: 100k. That's pretty impressive. A lot of people still like to actually hold something in their hands, something they can take with them to friends if it has to be. So while there are certainly a lot of people that will choose convenience over the best quality possible (blu-ray) there will always be people who demand a real product. Heck, there are still people buying (and hence producing) Vinyl LPs.
btw, are you Korean or do you just live there? I was born over there but grew up in Switzerland
