Micro-electro mechanical systems (MEMS) are extremely successful. You have them in your phone and lots of other devices. It turns out semiconductor manufacturing techniques could be leveraged to make some useful devices but that is about it. There is obviously a lot happening at these scales in biology, semiconductors, materials science etc but the grey goop of nanobots turned out to be a fantasy based on extrapolations that don't seem to hold up well with physical materials thankfully. One less thing to worry about. Now we only have climate change, pathogens, war etc. Hopefully the machine learning bubble will blow over in a similar fashion, genuinely revolutionary in some areas but increasingly difficult/uneconomical to scale into others.