You've just done the typical thing that people do - make a claim about something that's never going to happen.
They're not going to stop people flying their national flags, let's just not go down the route of even talking about that.
Personally I don't think you're entirely right about that. The true Europhiles believe that the EU flag should take precedence over national flags. If you take the principle of EU financing, on the face of it, the EU provides money for large infrastructure projects and those projects always have the EU flag on the sign and the legend "Part funded by the European Union" (or words to that effect).
In actual fact, what this is is money provided by one European country to another. Instead of, for instance, Germany lending €100M to Spain for a bridge, the wealthier countries give money to the EU, which costs a fortune for the administration, who then give it to other countries to use, which in turn costs yet another fortune.
You could argue that when there's a new sports stadium that receives EU funding, we effectively lend the money to ourselves and pay the EU millions for the privilege of doing it. If the EU bureaucrats had their way every country in the EC would cough up all their tax revenue for them to re-distribute as they see fit. The true Eurozealots firmly believe that this organisation is all that has kept the continent free from war. That's an easy argument to make bearing in mind that there hasn't been one within the EC area since 1945. However they've obviously never heard of a civil war.
Even then, that's an easy argument to defeat. The Spanish and Greek civil wars were before the Common Market was really up and running the the Jugoslav civil war was in an area outside the area. Spain was being fought over by a combination of Communists on one side and Fascists on the other. The Fascists were supported by Germany and Italy. Hitler and Mussolini managed to ensure that Fascism was removed from the political spectrum. Greece was also riven by fighting between the right and the left. The Balkans consisted of about 5 different nationalities all forced together into a marriage of (in)convenience.
There will always be differences of opinions and internal strife, whether it's Republicans and Unionists in Northern Ireland, or Basques in Spain, or even with the Walloons in the Nederlands, but the EU will never stop any of those simply by being a trading bloc.
There will only ever be one viable future for European unity and that's as a trading agreement, but then the Sepecat Jaguar, Puma, Gazelle and Merlin helicopters, and Concorde, not to mention the Channel Tunnel managed to get by without a massive, lumbering organisation behind it.
