I get that collapse is a slow ongoing process but when the history books are written, what do you think will be considered the US' own Battle of Ravenna? What will occur that historians can point to it and say, "this was the effective end of the American empire." ?
Yes, but 9/11 for a lot of people showed that the US mainland wasn't impenetrable. I remember hearing that from people expressing shock that "the most powerful country can have that happen." And this is from a non-American perspective.