Utterly theoretical question.
With a magic wand, the United States become Disunited into five or so sections, all of which are roughly the size of the major Euro powers (40-60 million pop, 1-2 trillon GDP). They are freindly democracies but not politically allied. As a side effect, the EU becomes effectively defunct. The rest of the world remains the same.
Is the world better off?
Many (including myself) would reflexively say yes, but there are things to think about. To wit:
[li]Could any world body (UN) effectively resist regional aggression, ala Iraq/Kuwait, Bosnia, China/Taiwan? [/li][li]Do financial markets benefit from having one or two markets/currencies as the “gold standard”?[/li][li]Would there be a global arms race? Many nations spend relatively little on defense because they know they are under the US defense umbrella. Would those nations feel a need to spend more without such an ally, and how would that affect their economies?[/li][li]Hollywood and American culture are global forces. Would the decentralization of that force lead to more tolerance, or more Balkanization? [/li][li]There have been relatively few periods in human history without one or two political entities who dominated the landscape, which begs the question of whether or not there is some underlying political force that inevitably causes superpowers to arise. [/li][/ul]