I use “nanobots” to mean “self-replicating microscopic machines with some fundamental mechanistic differences from all biological life that make them superior”.
I think that there are lots of plausible “invasive species from hell” scenarios where an organism is sufficiently edited so as to have no natural viruses (because its genome is weird) and no natural predators (because its sugars are weird or it has an exotic new toxin) and so on. They would still have ecological niches where they wouldn’t be able to thrive, and they would still presumably get predators and diseases eventually. But a lot of destruction could happen in the meantime, including collapsing critical ecosystems etc., and it could happen fast (years not decades, but also not weeks) if the organism is introduced in lots of places at once, I would assume.
Those scenarios are important, but they’re not “nanobots” by OP’s definition.
OP said:
I think that there are lots of plausible “invasive species from hell” scenarios where an organism is sufficiently edited so as to have no natural viruses (because its genome is weird) and no natural predators (because its sugars are weird or it has an exotic new toxin) and so on. They would still have ecological niches where they wouldn’t be able to thrive, and they would still presumably get predators and diseases eventually. But a lot of destruction could happen in the meantime, including collapsing critical ecosystems etc., and it could happen fast (years not decades, but also not weeks) if the organism is introduced in lots of places at once, I would assume.
Those scenarios are important, but they’re not “nanobots” by OP’s definition.