History shows us that all empires fail. The essay in the previous link shows the three phases of all empires; One; Growth, Two; Maturation, and Three; Decline and Failure.
It compares the same four characteristics for each Phase, and how they vary. The nature of the characteristics for Phase Three are: Land: Lose colonies, or control of other nations, by revolution or voluntary release (due to expense and unrest). Strength: No longer a world leader. Power declines by 50% or more, especially in foreign matters.
Value of fake currency crashes in purchasing power by 50% or more. Default on debt (or pay off with low value paper money). Government: Becomes weak, more corrupt, and desperate.
Leaders try to gain power (decrees, martial law, etc.) to survive citizen discontent. “Bread and Circuses” grow, now called grants, subsidies, stimulus, and entitlements. The army consists of mostly professional careerists, and volunteers, many of whom join because they can’t find work elsewhere.
Standards are lowered (criminal records, non-citizens, health issues) to aid recruiting for wars of empire (non-defense). Use of mercenaries and contractors grows toward 50% or more of total staff, and their loyalty is to their Generals (or Corporate officials), and original homeland, not the country that pays them. Ethics: Corruption and decadence are rampant in both citizen, business, and government conduct.
Failure occurs as the parent nation of the empire either; 1) Survives, but at a reduced level of strength and standard of living (England, France, Italy, Spain, Mongolia, and Russia are examples, or 2) Ceases to exist due to takeover by other nations or groups. Sadly, the USA fits all of the above characteristics of a failing empire!