There will certainly be more war in the Middle East (Iran vs Saudi Arabia, Israel vs Arab World), more war in Eastern Europe (Putin expanding into Crimea), more war in the Indian subcontinent (Pakistan is unstable), and so on. Is that the sort of world you want?
What the world needs to do, what Europe needs to do, is stand up on its two feet and quit being America's puppet. The same goes for pretty much everyone in the world. It is not good to rely on anyone else to represent your people and your economic interests in the world. Trusting other people's leadership is not a smart move, it keeps you incompetent.
edit: replying to the comment below.
So your point is that there is only enough room in the world for one ultra-national anti-internationalist country and the US is it. The end state of the game is when there is no such country in the world. That includes the US.
> "What the world needs to do, what Europe needs to do, is stand up on its two feet"
Advocating ultra-nationalist, anti-internationalist policies is, precisely, what leads to the mass conflict the grandparent was talking about.
There's no reason for the US to maintain the overwhelming global military presence that it does, particularly in Europe. World War 2 is over, and the US will never actually go to war with an enemy like Iran, Russia or China, or any country that might actually pose a legitimate threat to global security, so why keep up the pretense of being the "world's policeman?"
Btw, I do respect your points. I'm rather conflicted about this topic myself. We don't really know what the world would be like if the US were to practice isolationism - and we don't get do-overs for history if we mess it up. The powers that be seem to have decided that a forced stability is better than the risk of global instability.