I ain't no fancy engineer like you apparently are, but if you say these nanotubes can "repair themselves at the molecular level" - isn't that a feature normally found in things that are....alive?
Nanoscience involves with working at the molecular and even atomic level. When you get that small all sorts of interesting things happen.
Once nanotubes start to reproduce themselves, they will take over the world. They are 600 times stronger than steel -- nothing can stop them. They will consume human flesh and "mine" all living material, be it plant or animal, for the carbon atoms. They'll insert their tubular tendrils into our bodies while we sleep. No place will be safe.
But enough! I better get to work on the screenplay before someone steals my idea.