Not uninsurable, but buildings are going to have to become tougher. It's happened before. Chicago's reaction to the Great Fire was simple - no more building wooden houses. Chicago went all brick. Still is, mostly. The trouble is, brick isn't earthquake resistant. Not without steel reinforcement. I live in a house built of cinder block filled with concrete reinforced with steel. A commercial builder built this as his…
(This is not a contradiction of your point, just a useful related factoid for the modern era.)