I feel like 100 years is a little bit too conservative, especially since the adoption of new technologies can go extremely fast. A good example is the rise of mobile phones. In 1998 nobody expected people to walk around with mobile phones (check out this dutch interview:
https://www.youtube.com/watch?v=TNwhIHqM60g&t=17s). Little did these people know that only a mere 20 years later two-thirds of the worlds population would have a mobile phone connection. So there's absolutely no way it's going to take an entire century. It's either going to get adopted really quickly or it's not going to be adopted at all.
He make it 100 years rather than saying it on a short span of time because people would mostly react but actually it is somehow exaggerated and yes, technology adoption can really be fast but i dont really
see the possibility for Crypto to take over with fiat as long these greedy bastard government would exist they wont really allow such thing to happen since they do know on what would be the effects
if this thing would be implemented or changed.I would rather believe that e-currency would be utilize into those years and crypto is just always been an alternative.