America is kind of stuck in the "Common Ruin of the Contending Classes" trajectory; as was ancient Rome. It's likely not actually ever going to "collapse" internally, either to revolution, or mismanagement. Rather, institutional rot is going to become so pervasive that the US would simply not be able to defend itself from a foreign aggressor. It's already not really able to exert itself militarily (in a "productive", goal-oriented sense that is) against the world anymore.