Yes, things are bad. I don’t think that painting the bleakest, most depressing mental image possible is good for me though.
Furthermore it's probably wrong, too. Just after my mom finished school, some people were talking about how the number of diabetics is rapidly rising so that soon there would not be enough land to raise all the pigs required to get the insulin.
This was just before synthetic insulin was invented.
I read most of it (I would have preferred study links so I could look at the uncertainties but whatevs) and it basically just said, everything's fucked and our only hope is to go back to small scale agriculture (which would require massive, massive population loss).
Like, the next century is gonna be touch and go for humanity (certainly at our current levels of technological sophistication) but just saying we're doomed is entirely unhelpful.
Unfortunately, it's going to take us a lot longer to fix this problem than it did to create it. Hopefully that will be an important lesson learned for future generations.
As well as his/her proposed solution requiring most of the current population to die first as non-fertilizer based agriculture (certainly local agriculture) is really unlikely to be able to feed all of us.