The Botswana Model, or The Era of Zero-Sum

Der Spiegel is suggesting that Brexit negotiations between the UK and the EU will involve so many elements of strong disagreement, and such complexity, that a final deal might not be reached before the 2 year time limit of Article 50 expires:

"Negotiators in Brussels would like to see guarantees put in place that British and EU citizens will continue to enjoy the same rights that they do today. But ... it's clear that the British government cannot afford to show too much generosity on this front. Resentment toward the large number of Poles, Bulgarians and people from other EU countries living in Britain was one of the driving forces behind the Brexit vote. ...
EU Brexit negotiator Barnier issued a threat, essentially suggesting that if a Romanian nurse will require a visa to work in London, then John Cryan, who is from the UK, will also need one to work in Frankfurt. ...

The Europeans only want to discuss the free-trade agreement that Britain views as the core of its future relationship with the EU once solid progress has been made in negotiations over money and the rights of EU citizens. ... 
The promise made by Brexit supporters had been that Britain could continue to enjoy all the economic benefits of EU membership without any of the disadvantages that come with it. In the meantime, it has become clear that the EU would never agree to such an arrangement. ...

In total, some 20,833 laws and regulations that were in effect in the EU and Britain at the beginning of 2017 must now be reviewed and possibly replaced. ... It could, in other words, ultimately take much longer than two years before a deal can be reached. ...

British exports of foodstuffs and livestock would, from one day to the next, be subject to inspection, a development for which the EU member states do not currently have the capacity to handle at their borders or their ports. Chief EU negotiator Barnier has warned of the specter of long traffic jams of trucks at the British port of Dover.

In light of all these hurdles, the term "dirty Brexit" has long since been making the rounds in Brussels and London. This would be a divorce without a joint agreement in the event the Brits and Europeans don't come to some sort of a deal before the day Britain departs the EU in March 2019. ... the damage to both sides would be immense. Whereas the economic consequences of Brexit would first likely become visible in the medium-term in the event of a deal, a disorderly withdrawal from the EU could trigger an economic shock. ...

Is this what the post-Brexit world is going to look like? Bitter competition in the place of integration and cooperation? ... In their report, lawyers inside the German parliament came up with a sardonic name for this scenario: "The Botswana Model." One could also just say that, in the end, everybody would lose."