I would wholeheartedly agree. One need only look at 2 critical areas to see the potential for self-destruction: education and personal liberties. Regarding education, we seem to be purposely dumbing ourselves down. It is simply amazing how much our 12th graders don't know about our history, geography or the structure of our government - things that are necessary to make informed decisions (i.e. to vote) regarding foreign affairs. The population is becoming more willing to swallow the leftist/internationalist drivel that says that we should always be restrained in dealing with foreign nations. Second, we have long since begun to dismantle the precious liberties that the Founding Generation fought and bled for. As rightwhale mentioned, the key here is the 2nd Amendment. If it goes down the tubes (de facto, not de jure, as the latter won't occur), then our liberties will be gone in all but name. Abominations like the Patriot Act are bad enough by themselves, but they'd be even worse without 250+ million guns in civilian hands.
I am reminding of the following quote:
At what point shall we expect the approach of danger? By what means shall we fortify against it? Shall we expect some transatlantic military giant to step the ocean and crush us at a blow? Never! All the armies of Europe, Asia, and Africa combined, with all the treasure of the earth in their military chests; with a Buonaparte for a commander, could not by force take a drink from the Ohio, or make a track on the Blue Ridge, in the trial of a thousand years.
At what point then is the approach of danger to be expected? I answer, if it ever reach us, it must spring up amongst us. It cannot come from abroad. If destruction be our lot, we ourselves must be its author and finisher. As a nation of freemen, we must live through all time, or die by suicide.
Abraham Lincoln, January 27, 1838