The talent gap is still huge. The gap in the quality of players is not.
The results which have shown the U.S to be vulnerable in recent years haven't been because Spain, Argentina and the like have similar talent levels, it's been because most of the U.S. players have been dumb as hell. Much of which is attributable to the selfish, individualistic nature of today's NBA.
But see I think that only helps prove my point that the rest of the world has caught up in terms of being able to play and win games. Take a look at the players and teams from the 80's.
Bird, Stockton, Mullin, Olajuwon, Skiles, Harper, Petrovic and more weren't nearly as 'talented', at least in the way that I think you mean or what I often refer to back to when debating the topic of today's players versus past eras. Hell look at the Detroit Piston Bad Boys, were they very 'talented'? Maybe Thomas and Rodman.
Tracy McGrady may be one of the most talented players to ever play the game, but will anyone consider him in the top 50 players of all time, hell 100? Highly doubtful, because as you mentioned he didn't really play the game very well.
Just because you have a 48" vertical, can run a 4.4 40 and can sink 100 three pointers in a row...when no one is guarding you, doesn't mean that you are any good in a real game or when it comes to what is most important, winning.
So what if the USA has the most talent, if they don't play the game the right way, guess what happens, the rest of the world who may not be as physically gifted, but knows how to actually play team basketball, not sports center highlight reel one on one basketball, catches up and beats you.
Why do you think the US went to coach K? Because he knows good talent? No because he knows how to coach and play the game with the talent he has available to him. Players don't make him great, he makes them great.
I see the point you're making, but take a look at Mike Tyson, he could have been, and still is, talked about amongst the greats. But due to not having it all upstairs, he fell to a second rank all time great, not a first.
You have to have it all a the world has shown us, not just talent and natural gifts, but the smarts and will to win as well.