There is another option than either EU or UK dissolving. What about both? N. Ireland could vote to leave the UK and rejoin the rest of Ireland. Scotland could vote to leave the UK and remain in the EU. Meanwhile, Spain, Portugal, France, and the Netherlands could vote to leave the EU like the UK did. Switzerland's participation in EU treaties could get revoked. Belgium and Spain could vote to break apart based on their long-running internal divides. In the end, you might end up with a denuded UK and a denuded EU and a completely different map in Europe.