That ridiculous suggestion has been discussed already in another thread Khan. Boris showing he was less keen on overthrowing our lords & masters than he appeared before. Or perhaps it's just that he'd had a glass of vino or ten too many, maybe, and was everyone in the EU's best friend because he really loved them.
A break up of the EU need not be a disaster, it depends on how gradually it happens and how quickly a rival trading block (without the desire for European (or world) political domination) is up & running for countries to switch to.
That which is unrelated to the EU need not change. Although some may need monitoring to see if they are still fit for purpose. Some parts of membership were useful too, and can hopefully a convincing case can be made to let them remain largely in place. The change was always to stop being dictated to, and make our own decisions/contracts/alliances.