As I've posted herein occasionally, am very much of the opinion, there are far far far too many humans now on Earth for the health of both planet Earth and the human race. Getting humans to stop procreating even in individual countries is highly unlikely because of a list of obvious behavioral, social, economic, and religious reasons. But it is essential we do so and learn to live sustainably, else humans and our world are doomed, though it will likely be after our generation passes. Given so much warmongering, I doubt our race on its current path will avoid global thermonuclear war even during the current century, much less for a millennium.
At some point given how hopeless that is, I expect either an evil rogue nation or group will eventually create using CRISPR DNA technology, a weapons grade respiratory virus maybe atop one of our common cold viruses, far more virulent and lethal than COVID-19 that they themselves only have the antidote for.
Before releasing it given world wide transportation and the fact it could be contained in a small pocket sized vial, they might plant their bioweapon into large cities in all large nations across all continents and then under associated laptop computer with Internet control, electronically release it everywhere at once. It would take time for medical authorities to realize what was happening and shut transportation down, thus would spread to the point it would be impossible to stop until it ran its course everywhere. People would flee urban areas and create horrible dystopian chaos.
