Yeah, that is interesting. My guess would be that he's saying a single node could operate at that scale for less than the total operations of Visa. That could be true.

As for the "scale ceiling", I think he's arguing that there isn't a quadratic (or higher) growth in cost. Which I think is also probably true in general. I haven't seen a convincing argument against it at least. I'm aware of the quadratic cost in signatures, but that's as the size of a transaction grows rather than as the number of transactions go.

Really a very different perspective than certain key developers today who emphatically claim that 8MB is scary and dangerous.