I skimmed the RAND paper too and didn't come away from this feeling good at all.
There's a middle-ground for AI doomage which doesn't involve killing every last human on earth. As AI rapidly becomes more capable it displaces jobs faster than people can be retrained.
I fear a global economic depression, wider wealth inequality than ever before, a loss of benefits due to much lower tax revenues and greater imbalance of power, dismal job prospects returning to non-automated labor--the list goes on really.
And to connect this to the article: the experts who claimed that AI capability would slow down because of some "scaling laws" or whatever--they've been wrong. If anything, the progress is faster than most of us imagined and is only accelerating.
ChatGPT came out 4 years ago. Look at what's possible today. Now imagine 4 years from today.