This isn't new titillation. Daniel Defoe took his uncle's notes and wrote A Journal of the Plague Year in 1722, and it's still pretty interesting reading. Albert Camus' The Plague was an extensive examination of human behavior under that sort of stress - he denied, with considerable justification, that it was even an existentialist novel. I'm guessing, based on this, that the genre will be with us for awhile. And it indicates that although walking-dead zombies aren't real (however much fun it would be) societal breakdown and changes in human behavior faced with widespread threats to survival are. Laughing that off is whistling through a graveyard.
Oh, where I said zombies aren't real? I lied.
And our modern free love model will die when there are antibiotic immune STDS - several of which are already found in homosexuals.
In 2014, I saw the headline “Gonorrhea is about to become impossible to treat”.
If that and other STDs lead to someone suffering mightily, the easy sex exchange will stop in a way AIDS didn’t after anti-virals made it a manageable condition where the infected could live another 10-25 years.