I think it's going to be ~15 years before video downloads take over 50% of the DVD/Blue Ray market in the US so they have plenty of time to milk Blue Ray.
Dual Layer Blu-ray capacity: 50 Gigabytes. Verizon FIOS - 20 Mb/s for $70/month, or 50 Mb/s for around $144/month.
So, how long would it take for a person on FIOS to d/l this?
@ 20Mb/s: 50000MB / (20 Mb/s / 8 bits/Byte) = 50000MB/2.5 MB/s = 20000 seconds. Which is ~333.3 minutes, or about 5.5 hours.
@ 50Mb/s, you have (20Mb/s / 50 Mb/s) * 5.5 hours = ~2.2 hours.
Yes, you're not going to get full speed, but even a factor of 2 slowdown is faster than waiting for netflix.
So, it seems that the network required to do this is already being rolled out. For example, Verizon market penetration is outlined in a recent press release [1], indicating that Verizon will offer these speeds to 10 million subscribers within the next week or so.
As you said, it may be ~15 years, but I think it will be a lot shorter - I'd guess 5-7 years. I can't imagine that comcast is sitting around while verizon makes inroads into their userbase. They will counter, driving prices down and increasing market penetration for these high speeds.
PS: Once they started to send RST packets on non BT traffic I decided to jump ship so that BR movie is going to be 37hours for me.
EDIT: I only point this out because if your business model assumes most people will have 20MBit connections in 5-10 years you’re going to be sadly mistaken.