I will give a short answer and then ask Mr. Hyman to chime in.
As far as I know, if quantum is able to break blockchain technology, it would force the space to move to new algorithms that would be quantum-resistant. Some of that research has already begun. More worrisome would be that the entire Internet security would be broken today. Every banking system, every access layer and set of controls for pretty much every system that the government has and that users have would also be broken.
It's a scary world to imagine, but it's something that is important to consider.
Mr. Hyman, I don't know if you want to add anything to that.