The downfall of the EU could potentially allow for a successor framework that is more democratically backed. There are some that think the EU is corrupted beyond saving and it would be easier to start a new project instead of reforming the existing.

Personally, the fact that the EU considers itself above the constitutions of its member states without having this "constitution level" approved by the actual people (there are two referendums that failed at the ballot, in France and in the Netherlands, that lead restructuring so that no more popular vote was necessary, those are the contracts which are now in place), is a major no go for me. If there ever is to be an European constitution, the people must absolutely be able to vote on it, and the vote must be binding - so rejection means no, and a not "bypass by restructuring" - and a new attempt must then furthermore be voted on.