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?
mad max world is probably likely, or a 4400 type of civilization, where the rich are in thier bougie clean enclaves, while everyone is the devastate mad max style living.