I should probably weigh in on the nanodevice issue as well. Nanodevices will certainly evolve—as part of the rest of cultural evolution. However, what seems to being suggested is that any self-replicating nanodevices will be constructed in a way that they are fragile—in order to deliberately prevent their evolution in the wild, away from the intent of their designers.
I’m sceptical about whether this will ultimately be done. Today’s bacteria do not have such constraints placed on them—and most do not cause problems. Having your genome encrypted is a substantial competitive handicap—since it means you must constantly decrypt it—and you cannot adapt in the face of pathogens or environmental changes. IMO, those disadvantages will probably be compelling enough to eventually result in the production of self-replicating nanodevices that genuinely evolve.
Some other strategies will be used to help with safety. These days, many weserners constantly inject fresh gut microbes into ourselves—and the sheer rate of their influx helps to flush out any “old” mutant varieties. Also, there are plans to equip bacteria with both anti-bacterial compounds, and corresponding resistance genes. By cycling through a range of toxins, you can iteratively upgrade bacterial genomes, while killing off the previous versions—assuming no single bacterium can have all the toxin-resistance genes at once. Such a plan may eventually be used to defeat tooth decay. Similar strategies should work with nanodevices.