How can it fail? Well, it could go the same road Amiga did. The thing is not dead, they release a version in august 2011 if I'm not mistaking. It's alive... well sort of. Or like Betamax. It was seen as a better technologie (quality) than VHS, but the ease of use of the VHS and it's fast adoption of home user killed the Betamax. Sure, Betamax survived, as Betacam, in the  professional and broadcast video industry.

Don't get me wrong, Bitcoin is great. But it need too seduce the home user. For that, you need simplicity. I know I have to keep my bank pin number secret. But I don't need to worry about how I should make my bank account secure with encryption, backup and fire/watter/electromagnetic proof vault. If Bitcoin "fail", it's because it fail at simplicity.