One has only to look at the ideas and their manifestation that emanated from Europe over the last 100-200 years to know that a strong and successful Europe is in our best interests. Nationalism, Fascism, Communism and to some degree Imperialism (the British Empire) have all resulted in global catastrophes and 100M+ dead.
Unfortunately I believe Europe will fail and become more secularized, will sell out to radical Muslim and will degenerate, what they do about it is the danger to all of us.
They have the same problem we do, politicians who only care about getting re elected and not doing what's right for the country.