We are past the point where the weaponry available to the average civilian is sufficient to form a militia capable of holding back the armed forces, should the armed forces choose to cooperate in suppression of the civilian population. Syria doesn't have the capabilities the US forces do, and it shows.
So if the point of the 2nd Amendment is to defend the people from the government through the threat of the people taking up arms against the government, it can be deemed a failure.
The government is not a single perfectly cohesive faction. In extraordinary situations, people will do extraordinary things. Surely if you believe such a future is at all possible, then it would be pure insanity to relinquish the 2nd.
But even if you concede such a future is impossible and government is perfectly benevolent, it is the 2nd Amendment, it should be respected or repealed by proper vote, or else in defacing it you deface the whole document.
The reality is that these terrorist attacks (purposely inflicted mass civilian casualties) are horrible and appalling, but thankfully at least incredible rare, shocking, abhorrent events. This is not an excuse for indoctrinating fear into schoolchildren. The response to terrorism must be measured, considered, and appropriate. Or else the 'Terrorists Won', right? I see TFA, to some extent, as the terrorists have one.
Liberty never will but terrorism will. Anyone opposing will be classified as a terrorism, and trust, most people will believe that.
People can be very easily controlled. And rifles and will to nothing here. Think how many wanted to go to war and agreed to fight in Iraq. How many believed and still believe that Saddam was alqaeda. Or think about people consistently voting against their own interest.
It turns out the framers knew a lot about human nature, and the nature of government. Humans have done bad things with guns since long before 1789. This is something the framers considered extremely carefully and concluded the risks of an unarmed populace far exceed and outweigh the benefits of an unarmed populace. In my opinion, nothing has changed in this regard. If anything, the risks of disarming have seemed to increase dramatically.
IMO, fear of guns is highly irrational versus the fear of a government not beholden to its population.