"I think people really underestimate what it would take to actually completely exterminate our entire species. We already bounced back from a population collapse down to under 10,000 once, we could do so again. Nuclear war, ecological collapse, incurable disease; I highly doubt that any of them could kill everyone. Even if it’s just a few isolated pockets in the outback or the jungle that survive, that’s still not extinction.

Honestly, I think it would take a cosmic catastrophe (asteroid/comet impact, gamma ray burst, etc) to completely obliterate us and that assumes that it occurs soon enough that we don’t have viable populations outside of Earth."