I clarify:
Let’s say scientists can’t come up with solutions to global problems, AI gets out of control and turns almost everyone into paperclips during wars, and in the 2040s or 2050s, the surviving people (about a few tens of millions around the world or even less) gradually return to the level of intelligence of their distant ancestors?
Beyond a certain level of apocalypse we will probably need traveling network engineers, people who are willing to make the difficult journey between human habitats in order to repair and maintain network equipment.