I think you are under estimating the staying-power of DVDs.
The only reason that DVDs beat out VHS as quick asthey did was because of the inclusion of an onslaught of new and convenient features all at once. No need to rewind, being able to select a chapter, standardization of extra content, alternate audio tracks and camera angles, etc. It was a clear step forward, and even then, it didn't happen overnight.
Bluray's only offerings (currently) above DVD are higher storage space, HD picture, and scratch resistant coating. Storage space may matter to some people, who hate having to switch between ten different discs in one box set, but those same people would also prefer never having to change a disc ever with DigiDistro. HD picture is available either way, and, technically speaking, DigiDistro has the capability to have an even higher resolution in the future through software/firmware updates (Bluray does not, since it is not mandatory for all Bluray players to be updateable; one of the features that HD DVD DID have, but that is a seperate topic.) As much as I personally love the scratch proof coating on all of my Bluray discs (I believe I am up to 7 movies, two of them being two discs, and five PS3 games, so 14 discs total) DigiDistro removes any chance of discs getting scratched at all, of course it comes with the risk of corrupted data, etc, but implimented correctly, you would just be able to download the file again.
The point that I am gettingat is that by the time that the market is ready to accept the new features that Bluray offers, DigiDistro already offers all of that and more. Think about DVD-Audio, and how it never caught on, despite being absolutely superior. My father bought a car with a DVD audio sound system, and on the occassions I've borrowed it from him it's been an absolute delight to listen to my music in 5.1, but it just isn't different ENOUGH from a CD for the mainstream to care about it like they did the switch from tapes to CDs, or from CDs to mp3s.