I understand where you are coming from. With your feet planted in 2011, set in concrete, unable to fathom future developments based on the experimental or high-end tech of the day, the Blu-Ray seems endlessly of value. Much like the tape reels of the 60s.
The BluRay is going away for one very specific reason: mechanical. By 2016 the flash memory chips for 50gb will probably be so everyday and cheap that bulky, mechanical BluRay will seem awkward. By 2019 I'd bet you can store several times more than a BluRay on medium-priced thumb-drive.
Proof? Look back 6 years when a 1gb thumb-drive was a huge chunk of cash. Look back 10 years when a 512MB thumb-drive was almost prohibitive to buy. The future is non-mechanical.