Or any other hack which requires a rewind of the blockchain.

My thoughts are: yes. Of course, it would be terrible for bitcoin's PR. There would be potentially hundreds of thousands of people out of pocket (everyone who made a transaction after the rewind point), most of them with little chance of getting their money back. Bitcoin's price would surely plummet. But would it go all the way to zero? I think not. Unlike last time this happened (2011 I think?) there are literally millions of people out there with a vested interest in bitcoin's continued success. We wouldn't be so quick to throw in the towel. If this happened tomorrow, and after the patch and blockchain rewind the price dropped to say $50, would I be trying to sell the coins I currently own? Certainly not, I'd be buying more.

And furthermore, following a successful patch, the system would be stronger than ever before. In this sense bitcoin is 'antifragile'- everytime it breaks, instead of getting destroyed, it actually gets stronger and more resilient.

Would you rather place your trust in a system that had never been hacked, or a system that had been hacked X times and recovered every single time?