There is an essential divide at the heart of the European ideal (Germany v France v Britain) that would make it unlikely that Europe will ever be a true Federation like the US or Australia.

At the moment the only countries that count are Britain, France and Germany. No other nation has the same political, military and economic strength of these three. No other nation in Europe has the capacity to challenge them for leadership- and they have no compelling interest to see either of their rivals elevated to a position of authority. Put quite simply there are more reasons for maintaining the current arrangement which allows independent action.