Most likely the crisis will end with the UK crashing back into the EU, or at least into Customs Union and statutory convergence—but on EU maximalist terms with none of the opt-outs negotiated by previous British governments from Thatcher onwards. The negotiating position will most likely resemble that of Greece in 2011-2015, i.e. a vastly weaker supplicant in a state of crisis and near-collapse, and the British economy will take a generation to recover—if it ever manages to.
(This is, by the way, not the worst scenario I can envisage. The worst case is that the catastrophic collapse of the world’s sixth largest trading economy, combined with a POTUS whose understanding of economics is approximately as deep as that of Louis XVI, will lead to a global financial crisis on the scale of 2007-08—but without leadership as credible as, say, George W. Bush and/or Gordon Brown to pull our collective nuts out of the fire. In which case we’re looking at a global banking collapse, widespread famine due to those crop shortages, and a wave of revolutions the like of which the planet hasn’t seen since 1917-18. But hopefully that won’t happen, right? Because only a maniac would want to burn everything down in order to provide elbow room for a new white supremacist ethnostate world order. Oops, that would be Steve Bannon.)
I really, really hope that this grim take is wrong, but NC’s take is pretty similar. Theresa May really does seem like a simpering dolt, and the human cost will be enormous.