There were trade organisations before the EU, and there will be trade organisations after the EU. In fact, we went seamlessly from those to the EU (ignoring the will of the people even back then, of course). Going back to an organisation without political power could come to pass along the same lines, which would have the benefit of avoiding a no-deal fracturing and a few years of economic chaos.

Moreover, there is nothing that says regions like the Benelux, the Baltic states and the Scandinavian countries could have open internal borders (because their standards of living, cultures and political systems are similar, eliminating economic migration) and maybe in the medium term strive towards a political union as well.

The main issue is that Germany may become violent towards remaining EU countries to keep them in the EU. To deal with this, we should establish trade deals with the UK before the time is ripe to replace the EU so we can let Germany stew if necessary.