1nm isn't a special number just because it is 1. A nm is one billionth of a metre which itself is an arbitrary length so 1nm is a purely arbitrary cut-off.

What you should be asking is how many molecules of silicon and silicon-germanium can be packed into the spaces being talked about at the different fabrication levels of 14nm, 10nm, 7nm, 5nm, and so on.

Once you have that information then you can ask what is the smallest number of molecules that these processes can scale down to. Only then we can start asking about physical limits and more exotic processes. Are we talking about features of 50 or 40 molecules across or what?

All I know is that 1nm is not a magic number and that predictions about the demise of transistor scaling have always turned out to be wrong. My prediction is that, as unimaginable as it seems, we'll be able to scale down to the physical limits of the materials.