Anything above around 7 degrees of warming puts the human species itself at risk. Above 3 degrees civilization falls apart. Both of these are within range of possibility in the lifespan of children born today. All it would take is a few more Trump-style presidencies.
I think the OPs point is even then there would still be enough humans around to keep the species going. They probably wouldn't have todays technological benefits, but a few thousand humans could probably survive.