I recently read Catch 22 and it's a great book. While it is a little dated, it spawned a debate topic in me. In the book, an elderly Italian man asks a young American soldier how long he thinks his country will last, and antagonises him to an extent by saying that the United States won't last forever. Looking at history, it obviously won't. All the great civilisations declined. So, how long do you think the United States will last? What is our/their biggest threat?