There is the important question of HOW things will end - with a bang or a whimper. Like most people interested in survival/prepping/what-have-you, I start from an assumption of "Well, everyone else will be in trouble, but I'll be alright". Which is, of course, quite narrow minded.
How will things end? And how will things restart?
I have been thinking about a lot of PSHTF movies. Not a terribly good inspiration, or necessarily in any way based in fact or likelihood, more just something to irritate me.
For example, the Mad Max movies. Classic example of PSHTF. Great action films.
Except.
Except for the fact that the second and third movies are not possible.
For those not remembering, the second film sees the protagonist coming across an oil refinery in the middle of nowhere. No farms, no nearby villages (as far as we can tell), no food, no water, no hunting or fishing - nothing.
Third film - similar situation - a town in the middle of the desert. No obvious water supply (perhaps from underground), but no arable land, no food being carted in. Sure, there are pigs producing dung which creates methane to run generators - but where does the food for the pigs come from?
Both situations - impossible.
Where you have people, you have food. The more people you have, the more food you need - and the more your town is going to need much more farmed land nearby in order to support the town. Without mechanisation and transportation (let alone refrigeration), it's very difficult to support any urban population. And urban populations are important - they're the ones who aren't spending time in the fields, maintaining the farms, instead being able to invent, trade, produce culture, and all the other things we regard as marks of an advanced society.
We become so reliant on one another - when one tumbles, it's not a problem... when several tumble, it's too easy for the rest to fall.
There are a few movies which allow for some sort of PSHTF, agrarian society to have been re-established... but... movies are not about educating, but making money...
The point of this is - whenever you have a large group of people, you are going to have to feed them. Stop feeding them, and they'll either walk away, or test with you whether they like the taste of long pig.