Hello,
perhaps practical aspects originating from the blockchain layout such as what is the concept behind it is; what was it that was holding its implementation and deployment back for so long, and why there have been very few implementations of it until quite recently; how can future hardware and supercomputer developments affect it?
If this is not a strictly technical interview, reports, opinions and assumptions into the psychological and sociological aspects of the whole idea are always interesting to be heard.
Good luck with the interview-