After dismantling the last superpower, a whole spectrum of things could happen. The assumption is that whatever rises from the ashes just by chance is better than the system that has been refined and mostly thrived for two centuries. Of course there is no assurance that we won't be left with a mix of anarchy and warlords.
Not that I think Trump will bring that. The office of President is not that important. But I'm talking about what a certain set of voters says they want, not what will actually happen if they vote that way.
