I think (very illiberal sentiment here) that the world needs a ruler, and we need to be that one.
Trump is a transient spike in the ebb/flow of what the US is on the world stage. As has happened far more than once before. The next Executive will have a lot of sweeping-up-elephant-dung to do because of him. But the global order I don't think will be that much changed.
I, for one, am glad.