Can't cook the books if everything is on the Blockchain. When massive companies have failed, a la Enron, or experienced massive losses like GE, it's because of serious mismanagement and or fraud.

The thing is, if Bitcoin does crash in value and the big mining pools pull out, people will rush back in to take advantage of the reduced power requirements. I can envisage Bitcoin being pushed out gradually, but I can't evisage the technology actually crashing and staying crashed. I could be hilariousoy wrong though!