You are missing the economic component.. it isn't just how small can a transistor be.. it was really about how many transistors can you get for your money. So even when we reach terminal density, we probably haven't reached terminal economics.
I didn't say we have currently reached a limit. I am saying that there obvious is a limit (at some point). So, scaling cannot go forever. This is a counterpoint to the dubious analogy with deep learning.
