I agree that this is a key element to be considered a cosnitution, but shouldn't it include a certain power structure from the get-go to be considered one?.
Maybe the present power structure will still be a full political union if only the teatry would set a procedure based on European institutions (Comission, parliament and head of states)  to be amended, but it need to avoid the ratificaion by each one of the national parliaments.

At the end of the day, the treaty could say that it needs the ratification of all national parliaments, and then it would be no different than now.. and I would not call it a constitution.

A pleasure

I therefore claim to show, not how men think in myths, but how myths operate in men's minds without their being aware of the fact. Levi-Strauss, Claude