Always interesting.
There are two unique American characteristics that may yet stave off collapse.
One you allude to - the "survivalist" gun mentality. No, we are not going to barricade the doors to hold off the Obama Revenoor Collectivists but, Americans are still strongly disposed to telling the government, "don't tell me what the F to do!" If we did not have that disposition, we wouldn't be Americans. We'd be French. And yes, your points are well taken, it is possible that the populace may abandon their Americaness in favor of Frenchdom.
However, the other variable is G-d. Even when G-d was a Frenchman or an Englishman or a Muslim - He was the French State; or the English State; or the Authoritative Allah.
The United States was founded by a bunch of folk of all nationalities and religions that claimed that the one thing they had in common was that each individual had the G-d given right to his own individual relationship with G-d. We do NOT have to have the State as a mediator.
And, America is still the most Christian (or Jewish for that matter, outside of Israel) nation on Earth. There are tens of millions and more of hard core believing Christians (and Jews) who will refuse to let the State tell them that their G-d is illegal and must be abolished.
If push comes to shove, it will be these folk from whence the revolution comes against America becoming a new Europe...