I think in my area it was pretty broadly assigned reading at the time - lots of other high schools in the US assigned it - though no idea if that’s still the case (the book certainly isn’t perfect - the female characters are incredibly one-dimensional) but I hope it is still commonly read.

I see On the Beach as being Threads-Lite. On the Beach is certainly upsetting but wow, does Threads show a more upsetting version of similar dynamics. Plus none of the characters of Threads are as uncomplicatedly virtuous as the characters of On the Beach.