I've been in technology long enough to know that there's no system that lasts forever in technology, so when something comes along that inevitably makes blockchain obsolete, or we discover that it isn't actually secure after all and there's some major vulnerability in the whole algorithmic process, how hard is it to get that cumulative historical data out of it and into the next system? If it's all cryptographically signed, how are we going to get that entire history back and salvage it?
On October 31st, 2018. See this statement in context.