It was an interesting debate. Roubini whose point of view has always been anti-crypto spoke highly of centralized private payment systems such as Alipay (China), M-Pesa (Kenya), Venmo and other mobile payment systems. His entire approach seemed to be underpinned by trust in authority, which I believe is unwarranted in much of the world. Van Valkenburg talked about risks involved in having a single point of failure multiple times bringing up the Equifax hack in the USA, for example. He also mentioned Alipay as a perfect tool for totalitarians as it is a simple database the government of China is able to completely control.
Roubini made some good points, too. He said multiple times that the blockchain is necessary only for buiding a trustless consensus mechanism. A private permissioned network does not need a blockchain to build a ledger as it would be wasteful. Roubini also mentioned the fact Chinese mining pools account for 70% of the Bitcoin hashrate. China being a totalitarian state, that makes, Bitcoin vulnerable to the Chinese state. That is actually concerning as it shows that Bitcoin is lacking decentralization.