If the idea of a CBDC is implemented to its full potential, it will strike against today's bankers (not central bankers, though). Really, if people will be able to transact directly through a central bank (as Roubini suggests), what is going to happen to commercial banks?
Well, currently, central banks use RTGS or other techniques. Central banks will settle transactions if the transfer occurs between different commercial banks afaik. Perhaps the CBDC only renews the old RTGS system. Commercial banks still do what they do
best poorly, e.g., giving loans.
how can they hurt Bitcoin beyond what regular fiat already does? People will see the advantages of a CBDC, but these are also the advantages of Bitcoin, divorced from the CBDC's disadvantages (most important, inflation)
What made I'm interested in Bitcoin is for remittance or commercial usage across countries. At the moment, PayPal sucks, and Bitcoin is the cheaper solution for that purpose. If CBDC can somehow make remittance and international commerce easy and cheap, we will lose these markets. Since we already lose the "buying coffee" market due to the scalability problem (the so-called trilemma), the one who stays here will be the "e-gold" and the gambling market, and it's niche.