UN functions
The U.N. could work just fine as a forum for organizing humanitarian assistance, discussing trade rules, and other such things. It just sucks in its "peacekeeping" role.
The place would also need a housecleaning.
Raoul pointed out that a requirement for joining the EU was adherence to certain principles. In the original treaty, they are laid out (Article 6) as: "...the principles of liberty, democracy, respect for human rights and
fundamental freedoms, and the rule of law..."
The U.N. could do worse than raise the bar for membership at least that high.