@ 45. Fabius: “But I worry that the backlash will be extreme.”

Extreme? You mention only the political manifestations of extremism. If, and that is still a monstrous if, this backlash occurs the excesses will make your skin crawl. Think of Vlad the Impaler, the Thirty Years War, the Inquisition, the WWII labour/death camps.

Extremism is something not foreign to the European. Nevertheless, I betting on 1. Europistan, followed fairly rapidly by 3. Europe ceases to formally exist in any recognizable state.