So that's the keyword there, obviously he wanted to have a lively discussions and perhaps he just quip that statement to please the crowd, so I will take everything with a grain of salt here.
As a relatively young economist, maybe he is really open to the idea of cryptocurrency but he knows where he speak and the global realities that we are in that is why he predicted that maybe it can happen 20 or 30 years down the road. And given the fact that many governments are not yet that open on this platform which would surely affect their control of the economy, 30 years may not even be enough for bitcoin to gain a broad acceptance. What is important here is that right now, there are now an increasing number of prominent people and leaders of different industries who are more inclined to believe on bitcoin and cryptocurrency...this is important in the shift of the paradigm. Just like terraforming Mars, it can take decades before seeing the silver lining on the sky.