Not a good example. Lets just say we left right after we blew the place up. You cant equate whats going on in Iraq right now with all out war. If our goal was to defeat Europe...not colonize it, we could do that.
How are they going to outmanufacture us with their major highways bombed out and factories destroyed in a protracted war?
If your goal was to defeat Europe, when exactly would you declare victory? Would it be when you currently had military superiority, but Europe still had the capacity to outproduce and then defeat you? Because you may as well do that now.
The way to stop Europe destroying you is to conquer and hold the landmass, which is something that America is simply not equipped to do. Iraq is, therefore, a good representation of the problems that you'd face.
Or maybe you think that Europe has no airforce or ballistic missiles either? Europe has no friends in the world, because everyone really loves the US? Iceland is clearly American, because it's actually a Danish colony? One airbase doesn't make Iceland American.
Where will you find all the airpower to send bombers to bomb all the highways in Europe, remembering, of course, that European countries are densely packed with roads, such that it's impossible simply to bomb a few roads to stop traffic?
There is no way that America could hope to come off better from any aggression. Of course, Europe currently has even less of a hope of being aggressive. However, initially it would likely be a tie, and then it would come down to allies and production, both of which Europe would probably win.
Finally, you never explained how you'd destroy the factories and roads you seem so confident of effortless targetting. You'd probably hit all the Chinese embassies instead.