How difficult or easy is it to imagine McCarthy's nightmare vision of The Road actually happening?
Cormac McCarthy envisions a post-apocalyptic world in which "murder was everywhere upon the land" and the earth would soon be "largely populated by men who would eat your children in front of your eyes" [p. 181]. Do you think people would likely behave as they do in the novel, under the same circumstances leading civilization towards a brutal end?
It is a very subjective consideration to wonder whether the world could ever end in a way envisioned in The Road. Historically, mankind has been warned by all the religions and spiritual heads that we will face an unthinkable end if we continue on this destructive path.
It is true that even now, "murder is (was) everywhere upon the land" although, even in the most desperately poor regions of the world, except in a cultural and ritualistic fashion, people do NOT generally "eat your children." This observation would lead me (in my opinion) to believe that - on a large scale - this situation is purely fiction.
Movies and fiction novels are keen and often meant to sensationalize. Unfortunately, we are not that affected anymore by man-eating sharks or oversized gorillas so need much more to spark the imagination. However, even eating your colleagues after a plane crash is not enough to satisfy the human appetite! - an unfortunate or maybe fitting choice of word-(appetite).
The way Cormac McCarthy uses seemingly separate events throughout the world and brings them together in order to almost guarantee destruction - ash clouds, perpetual winter and altered weather patterns, hunger, desperation, anarchy - all these events are themselves huge and potentially catastrophic so for all of them to be in one place is monumental.
We see the efffects of riots when large numbers of people render the police ineffectual and looting takes over, buildings are burned and people are caught on camera committing unthinkable deeds. When they are caught, society is shocked that they got involved. So yes, it is possible for "ordinary" people to lose - but perhaps only momentarily - their sense of right and wrong.
We see the effects of climate change and previously lush land turned into desert. We see tsunamis and earthquakes swallow people up and destroy lives. We see, despite our best efforts how children still die of starvation in this world of plenty. We see evil men and women harm children in the most unthinkable way BUT even Cormac McCarthy left us with hope of something beyond the scope of the world he created. By creating characters that remain "the good guys" in the face of this destruction also provides a glimmer of hope.
On a small scale, man may lose his direction and even lose hope - the man and boy are largely unaffected by the presence of plant life towards the end as they have lost focus and don't even know why or whether they survive to this point. But still the father has hope for his son and is determined that the "fire" does not go out, enabling the boy to find something better.
The randomness of the man's appearance at the end - the possibility of a real family - and the unquestioned goodness of the family also provide for the belief that random acts of kindness will endure even in the most unimaginable hardship.