There are several possible ways how current pandemic may turn into a civilizational collapse (which may be the first step of an extinction event, depending on the possibility of recovery). I will list below several putative ideas of how the pandemic could turn into a global collapse. Each of them, I guess, has lower than 1 per cent probability:
Inevitable reinfection. The virus has an ability to mutate inside the body causing deadlier reinfection later with the “personal strain"; If true, most infected will die in a few months. This is how feline peritonitis coronavirus kills.
New strain. The virus will mutate globally in a new strain, which will be deadlier, or more affect children, or better evade quarantine and sanitation.
New waves. The virus is mutating so quickly that the vaccine is not possible, and each year will be new waves of reinfections, with mortality of a few per cent each.
Famine. The virus could be contained, but only via global lockdown. The economy as we know it will collapse and eventually famine and other forms of shortages ensure. Alternatively, the virus is not that deadly, but social collapse will happen anyway as a combination of border controls, riots, civil wars.
Infertility. The virus causes long-term health effects for most survivors, like infertility, reduced lung capacity and brain damage. This gradually reduces human potential and civilisational productivity.
After-the-fact analysis of the causes of major disasters often reveals multiple independent causes, none of which would have caused a disaster by itself, but each of which degraded or disabled the usual safeguards in place for the other problems. This seems to come up in everything from relatively small-scale transportation disasters to the fall of civilizations, and possibly in major extinction events. E.g. there have been many large asteroid impacts, but the one which finished off the dinosaurs happened to also coincide with (and possibly triggered or exacerbated) major volcanic activity. (The Deccan Traps.)
So the worst possible outcome of the epidemic might be that it happens to coincide with some other, totally unrelated disaster. For example, natural disasters such as earthquake+tsunamis, widespread rainfall and flooding, major fires piling air-quality issues on top of COVID-19 breathing problems, and so on. (In a way, I'm thankful the recent fires in Australia happened then, and are therefore not happening now.) Unrelated war(s) would make everything worse. So would a second pandemic at the same time. So would just about anything on the list of possible existential risks. I think this would count as a worst-case outcome of the epidemic, even though it would be an indirect outcome.
The global scale of this epidemic, and its months-long projected duration, seem to make it more probable that something else will go badly wrong just when everything else is under stress.
Yes, and there are biggest locust explosion in 70 years now.
1philosophytorres
Also worth noting: if the onset of global catastrophes is better, then global catastrophes will tend to cluster together, so we might expect another global catastrophe before this one is over. (See the "clustering illusion.")
I once took a look into the clustering illusion, and found a research that in the interconnected systems it is not an illusion: any correlation increases the probability of clustering significantly:
Downarowicz, T., & Lacroix, Y. (2011). The law of series. Ergodic Theory and Dynamical Systems, 31(2), 351–367.
There are several possible ways how current pandemic may turn into a civilizational collapse (which may be the first step of an extinction event, depending on the possibility of recovery). I will list below several putative ideas of how the pandemic could turn into a global collapse. Each of them, I guess, has lower than 1 per cent probability: