The eastern Empire, with some bumps in the road, lasted almost another millennium; Constantinople finally fell to the Turks in 1453.
The thing that really killed the western Empire was "offshoring" their national defense. The more your army is made of up of paid foreign mercenaries, the more tempted they are to simply plunder their employer instead of waiting for a paltry payday.
Do you think that is the future of the US military if Trump loses?