Interesting premises you proffer. Re this: "Once the safety net of society has finally broken down we will be forced back into the bad old days of dog eat dog, where sex trafficking is rampant...." Ummmm...how is that really much different from now?

Anyhow...I think the amount and speed of population reduction will be a major factor in what happens after that. In future scenarios like the recent "Station Eleven," or the classic "Earth Abides," a pandemic massively reduces human population very quickly. Which is perhaps better, for those left alive, than for example collapse of industrial systems with no pandemic, resulting in mass starvation as primary cause of population reduction. None of it a cheery prospect, alas.