Nice try, but you have a few ingredients missing in your 'concrete'.
There were no nukes in hands of the enemy then, there were no jets to be hijacked and flown into cities, there was no well funded radical islam, there were no computers, no cell phones, no internet, no electronic banking system, no satellites, on and on and on.
The world, and thus the threat, has changed my friend. Wake up and smell the coffee.
So this means we should just abandon democracy and let a dictator rule? There have always been threats - Washington DC was burned down during the War of 1812. The Confederacy made a good try at doing it again during the Civil War. We lived under the threat of nuclear anihilation during the Cold War - all without demolishing the Constitution.