If modern civilization regressed due to, or was destroyed entirely, by one or more global disasters, say, a more lethal variant of rabies reaching pandemic status, coupled with a short-lived but high-intensity conventional world war ended by a handful of nuclear destinations in major cities, followed by a two-year famine, what elements of "Pre-Fall" society would rise to power and pick up the pieces?
The other day, me and a friend of mine were having a fairly lengthy debate on the subject, on the US in particular. I figure Utah, having a large Mormon population, would quickly organize into a theocracy, that would soon become rapidly expansionist to conquer enough farmland to feed itself, and that various extremist political /religious groups would secede in the event of a world war and begin to carve out their own territories, in a way not dissimilar to ISIS. My friend is convinced that upon the collapse of the Federal Government, the military would fracture into several dozen rogue factions, the loyalists being, if not the largest, among the largest, which would immediately begin to either carve out their own pseudo-fiefdoms, loot and pillage the countryside, or work as mercenaries for surviving settlements. He's also convinced that the majority of the US's prison population, 3 times the size of China's military, would escape and organize into large marauding gangs and begin to exert their influence, like a less efficient and poorly equipped, but more brutal version of the military factions. I feel that's extremely likely, but I felt I had to get Veeky Forums's input, hence the questioning thread title. Thanks in advance for answering.
> tl;dr: If shit hit the fan and civilization collapsed, what kind of factions would takeover and become the new government?