In America I think that democracy will cease to exist when the underclass realise that they are being used by the masses and that they have all the guns. Think LA riots on a slightly larger scale.
The basic problem with your form of capitalism is that it uses people then discards them. It demands a large pool of unskilled low paid slaves who can be used and abused - and if there aren't enough people then open the immigrant floodgates. There is no American dream for the tens of millions who live in abject poverty, get poorly educated, have no medical care etc etc.
BTW its not much better here in Europe, but our basic sense of humanity doesn't allow us to have such a crushing divide between rich and poor AND blame the poor. I was in Washington in September 1998 and the schools stayed closed because money wasn't there to carry out basic maintenance to make the crumbling buildings safe to reopen. How can the "capital of the free world" treat its children which such contempt? Capitalism has advanced the world in so many ways, but its excesses have to be tempered. Currently we have a global crisis of capitalism created by bankers who got rch by selling credit to the poor. Large scale unemployment - and its going to get worse if our idiot European leaders cut spending - has millions desperate to work and unable to find any. You want to threaten democracy? Tell people that they have to stay on the floor whilst those responsible for putting them get ever richer.