Fox has a list of 10 obsolete techs - the story is interesting enough, but this bit on DVD's caught my eye:
What's that, you say? How can DVDs be obsolete? Facts don't lie -- DVD sales fell off the proverbial cliff in the first three months of 2009, with some retailers reporting a 40 percent drop from the same period a year earlier.
I suspect that Blu-Ray will just never catch on big for the same reason given for this: broadband and downloadable movies. You can stream and download easily now, and without having to worry about BitTorrent and legal issues - iTunes, NetFlix (et. al.) are quickly becoming the go to spot for this.
The next wave of problems this will cause will be to cable and phone companies that provide broadband and TV. They want you to buy "On Demand"; you'll want to stream. That's where the current cap argument is based, I think - if they get driven to being nothing more than a pipe, they transform from having huge margins to being a normal business with tight margins.