Economic collapse is already happening in lot of the countries all over the world, yes it is slow, and may be not so visible everywhere, but it is there.
Since everything is so connected in today world no country can be spared from that results, if economic collapse happen in US it simply must affect all other parts of the world, OK some countries and economies can last longer, but everyone will feel that.

Do not underestimate will of powerful people to keep their power, some scenarios are different but some things in that scenarios are common, fight for resources, finding “guilty” people for what is happening etc.

At the end there are gonna be bunch of people fighting for resources and power, and that is it.