Clark is such a true American that I can't see him moving away, or at least not far away, from the United States for long. (Mexico City might do. He could help stopping the drug war there, perhaps.)
You have to wonder, though - what if the US gave Clark so much hassle that he decided to move to a country farther away, a country that the US might even regard with some suspicion? Like China? Or even Russia? I know, that wouldn't ever happen, not with Clark being Clark. But, just for the sake of the argument, let's imagine that it did. How ould the US react? Would they demand that Superman return? Would they, perhaps, even issue a threat to the country that currently 'held' Superman?
This reminds me, more than ever, that the world was a simpler place at the time when Superman was created, back in 1934. (Yes, Siegel and Shuster came up with the idea of Superman in 1934, but their character was "officially" born in 1938, when Superman was introduced to America in Action Comics #1.) Consider though - back in 1934, there were no atomic bombs. Not in 1938 either. Back then, Superman couldn't have caused the kind of international crisis that he could indeed have caused if he had existed today, if countries had fought over him. After all, Superman would be, potentially at least, the world's most powerful weapon!
Ann