Reverso/Ditranko on the end of Superman as a viable national emblem, and the rise of Captain America as a better metaphor, and more brain-expanding stuff, at Millarworld of all places. Not a venue known for deep philosophical discourse, unless you count "uh, DC sux, Marvel rools".
Of course, I reckon Cap is a better symbol for the U.S. because, as a character, he is so utterly of the military-industrial complex. If once we dreamt of America through the metaphor of the ultimate immigrant and his second chance in literally, the new world, now we perceive it as defined by war. World War II, The Cold War, the War On Terror - America keeps its economic blood pumping by being in a constant state of conflict, however ill-defined. I don't hold it against it - so did the Romans, and the British, in their imperial phases. Therefore, the better, truer, embodiment of the country is a career soldier. And Millar's "Ultimate" take on the character rings truer than most: deeply conservative, macho, swaggering, French-baiting. Basically, he's John Wagner's Judge Dredd, only prettier. This, of course, has been deeply horrifying to many American reviewers, especially those of a liberal bent. "Captain America should be about the American Dream, not the American reality". Sorry chums, but that's how most of the world sees you these days. If you don't like it, do something about it.