I don't think impeachment was much in vogue during the late Roman Empire: Most regime changes were pretty sticky affairs one way of another.
I believe we are going through this just like Rome, slow but steady decline, with the same outcome; however, most empires fall, sooner or later. Wonderful book called 'The Rise and Fall of Empires' (Kennedy) for those of you who wish more reading. While it won't be a Dark Age it will be one of havoc and strife. Say what you will about empires but they do bring stability which bring advancement in all areas; agriculture, medical, engineering, etc. EDIT: BTW I personally think the major reason for decline and finally collapse is and will be - corruption. Very good video, Chello. Thanks!
Not Rome, because we will not be invaded and broken up by the barbarians. We will I think go more the way of the British, French, Spanish and Russians. Most of these countries, like the USA, have nukes and are safe from invasion by foreign armies. The populations may change over time due to immigration and birth-rates. The biggest threat to the USA is China and our own barbarians (BLM, ANTIFA, etc.), but in the worse-case I got preps for that...I'll just become the local war-lord...I even got a place picked out for a hill fort.
I could see an overpass being turned into a fortress. You would have access/control of the roads, be able to exert your authority, collect taxes, establish a market town, etc....all the things necessary to create your own feudal fiefdom. PS I read the entire "Dies The Fire" series.