Nanotech "assemblers" are coming in a sense, but they got the scale wrong. They're called 3d printers and they operate at the macro scale, but they are not really any less disruptive.

As far as true nanotech goes, we've had it for about 4.5 billion years. It's called biology. You are basically made of nano-assemblers holding hands. Genetically engineered biology and "wet artificial life" are engineerable nanotech, but if you want to see Turing-complete universal assemblers in action right now go plant a tree.

In other words, I sort of think nanotechnology is a useless neologism for biology and bioengineering and I doubt that anything other than carbon-based systems are going to do much better than biology... and those are basically synthetic biology.