Very true. When CD-ROMs first came out, 650MB was unfathomably huge, in that era where PCs had 1-2MB of RAM and hard disks were in the 10-20MB range. Blu-Rays have about 50GB of space, but PCs have 8-16GB of RAM and 1-2TB disk drives. They'll presumably have the same durability that optical discs have always had, but they're not going to be able to back up a typical person's data without using multiple media. That means either manual disc switching, or jukeboxes that are either expensive or mechanically flimsy.
They're talking about the end of 2015. Even if they meet that schedule (unlikely--they may get the technology developed, but you still have to allow a few years for everybody to finish suing each other), they would still need to be something like 3-5TB to be useful as backup media.
Just being able to stuff all eight Harry Potter Blu-Rays on one disc isn't enough justification for Yet Another Disc Format.