As an Express (U.K.) story reports, Brexit is officially "on," the letter beginning Article 50 has been delivered to the EU. The negotiations and machinations over the next two years will make fascinating history, live and on-camera. We expect to follow it relatively carefully, if not daily.
Inasmuch as no nation has left the European Union until now, there is no precident, no history to help us understand the kabuki in Brussels. Both the EU's negotiators and those for the United Kingdom will make it up as they go.
One of the questions raised is whether Brexit is a one-off or the first of several exits? Realistically, for economic reasons Greece should leave as should Italy. For quite other reasons, Ireland will think of leaving. In its case, their love-hate relationship and close economic ties with the Brits makes doing the same as the U.K. a real possibility.
Brexit has caused a resurgence in agitation for Scottish independence. Hoping to forestall Catalan desires for independence, Spain has threatened to veto any move by an independent Scotland to join the E.U. as a way to signal the Catalans they would similarly be barred. A novel event, Brexit is generating second and third order indirect consequences.