This article is spot on. The Yurps are overplaying their hand here. If Britain leaves with no deal in place, it is their huge trade surplus with Britain that will get it right in the neck.
Meanwhile the Italians and Eastern Europeans will continue to just thumb their noses at Berlin/Paris.
Meanwhile, the EU has launched its SPV with Iran: INSTEX.
Nice allies we got there, eh?
The EU is perfectly willing to have a trade deal with the UK, but if the UK wants something like Norway or Switzerland has, then it needs to allow freedom of goods, services, capital and EU citizens. If they want something else then they need to negotiate the terms just like anybody else
The UK under WTO terms will be just like everybody else. They will not "do fine" - but they won't collapse economically yet. They will have a hit of anything from 2% to 4% GDP in the 2 year horizon. After that, it all depends on how well their government manages it
But that's the crux - May has NOT managed anything so far, so expecting her to manage the no-deal Brexit is a larf