Did you read the landmark Action Comics #900? If so, you would have come across this little sequence, written by David S. Goyer, that surely won't find its way over to Fox News for any reason whatsoever. (UPDATE: called it!)
Just like that DC, has a heck of a possible controversy on their hands. People got very mad about Wonder Woman's costume change, and the death of Captain America, so why don't people seem to be up in arms about this one? Superman is the original superhero. He counted as an American, even though, he's technically an illegal immigrant. How did the Kents secure a birth certificate anyway?
The subject of Kal-El's American-ness isn't something writers have shied away from over time however. He was cast as the tool of the corrupt government in Frank Miller's Dark Knight Returns. He took plenty of guff from Diana in Darwyn Cooke's New Frontier, and in continuity, DC made super criminal Lex Luthor the president of the United States.
I've noticed that Kal hasn't actually done it yet though. He says he's going to. All sorts of things could happen between now and that UN address.
Does Superman belong to the world, or is he American? Is the world smaller, and are Superman's allegiances greater to those of the U.S. than of the rest of the world? It's a can of worms that will yield all sorts of things a storyteller can use, but the question is really whether it will contribute to stories that comic book fans will want to read? Time will tell.