If it ever falls to $1 then most likely it will be finished. When it crashed from $20K to $3K that is not so far fetched since it was $1K the year prior, however if it ever were to hit $1 then all trust would be lost and most people wouldn't touch it.
If you want a good example, look at most penny stocks. They are ultra cheap, basically fractions of a penny. People buy them thinking that if they buy 1 million shares of some bankrupt company for $100 and if it goes to $1/share they will be millionaires however that never happens. If bitcoin went to $1 then it would be the same scenario.
Excellent point. If Bitcoin goes to $1 again any number of "better" coins (quicker payments, smoother transfers, more user friendly) would eclipse it. Bitcoin is the most powerful because it is the original crypto.
It is very doubtful bitcoin will reach $1 any time soon, but if it does it is virtually "bankrupt".