Is the world becoming uninsurable?

That's not really true. The introduction of so much extra energy into the atmosphere is going to make weather extremes worse all over the world, and harder to predict as historical models become less relevant. Large scale pattern changes like the AMOC shutting down are going to completely change many local weather patterns so that e.g. places that have little history of tornados will start having them, or places that used to be too wet for wildfires will suddenly experience them in extreme drought conditions. Despite scientists' best efforts, we're running a global experiment with no control group and predictions will only become more difficult the harder we push the system into a new state.