Difficult to predict the future, but we know the present in the EU.
We do know that any friction caused by regulatory differences and tariffs will be detrimental as they involve more costs and less efficiency.
We don’t know how long it will take and how beneficial it will be to make new trade deals. We do know that it won’t be as quick or easy as promised. We should realise by now that negotiating trade deals from the position of a distressed trading partner is a poor negotiating stance.
Based on that, remaining is the safer option.
It is difficult to predict the future whatever happens.
The EU needs us more than many realise or care to admit. The problem is that they can't be seen to be weak. And they also need to keep the money rolling in. Let's forget about the money for farming subsidies for now. An MEP is on over €7,500 A month IIRC. There is about 750 MEP's. So about €67,500,000 A year in wages. Then you have thousands more working in the EU. IIRC they get a pension of nearly €30,000 For just 10 years work. The more years the higher the pension. How many already have pension rights or already collect a pension not available to the paying public? So the pension bill grows by about 2m a year without inflation. And this is only for MEP's.
Most countries in the EU are struggling. It is mainly massive debt, high unemployment, recession or more than one of these. Yet if we leave this money has to be replaced or saved. If saved it means working out where it isn't needed. If it isn't needed it shouldn't have been paid out to start.
And before you say it this isn't an anti EU rant. It is the main reason I see the EU wanting a deal however much they posture and make out they don't need us. They don't exactly need us but it would cause many problems without easy trade with us and the money we hand over.
It is the same for the UK. We don't depend on easy trade with the EU. But it would cause many problems if we leave without a deal.
We could sit here for days listing the problems caused for both sides. Both would most probably survive without each other. But it would be a disaster for some companies and areas. This is both sides of the channel.
So yes it would be utter madness for both sides to spit their dummies out. It is like a poker hand where neither has a good hand and are both trying to bluff. And both are crap at bluffing.