not sure why you keep arguing ugo - the reality is that similar US teams have been beaten more than once in the past 10 years. So it is possible. And those teams were featuring just as much starpower as the current one. Obviously USA has the best players in the world, and they are big favorites against any opponent (you could probably argue that if USA fields 10 teams, they could potentially go 1-10 - that's how deep they are). But still -they are not invincible.
During the past decade, they have shown a few weaknesses, 3pt shooting, pick and roll defense, free throw shooting, focus and intensity - these are areas where they were NOT the best in the world. When it comes to speed, strength, agility and stamina, there is no country coming even remotely close.
So the bottom line is that while the americans are by far the best, they are not the best AT EVERYTHING. So once in a blue moon, they can lose. Especially if they are not 100% focused.
Also, I think the current team was really the best they could field. Duncan doesn't do well in international basketball, especially with the guard oriented style employed by the USA. And at 1, 2 and 3s, they had the best players in the league. So I'm not sure whether having KG or Duncan would have made any difference whatsoever.