A chaotic Brexit, in which key questions about the relationship between the UK and the EU are left unanswered, may be avoided, but severe political and economic harm could still await both sides. What, then, accounts for the evident lack of urgency in taking the necessary steps to avoid such a scenario? — By Jean Pisani-Ferry PARIS — On December 8, the United Kingdom and the European Union’s 27 members settled on some key aspects of the Brexit divorce agreement, opening the way for the decision, on December 15, to open a new chapter in negotiations, focused on addressing the future EU-UK relationship…