For the UK this looks like finally the end of five years of turbulent politics dominated by the EU relationship. Three consecutive autumns dominated by the question of deal or not. The question has for the time being been settled, with a preferential relationship greater than WTO but less than customs union or single market. There will be continuous negotiations on areas of detail in the future, but most will barely trouble the media or political worlds. Overall there will be some form of stability, even if uneasily in a UK split between those wanting closer and more distant EU relations, and with particular challenges in Scotland and Northern Ireland.
There will of course be major challenges in the future relationship. Ultimately the EU achieved their main goals from Brexit, and the UK arguably did not. The EU successfully avoided a border on the island of Ireland and protected the single market from significant cherry picking. The UK succeeded in the headline goal of leaving the EU, but failed as proponents had expected to retain the benefits of membership without incurring the costs, and more recently in overturning any of the withdrawal agreement as the staunch Brexiteers had hoped. The EU also looks stronger for demonstrating so far that leaving is not an easy option, while the UK’s ability to maintain trade relations while escaping ‘the Brussels Effect’ of following EU regulations is going to be tested, business for example will wish to reverse the decision to leave some European regulatory agencies.