Cryptocurrency doesn't have to be direct "competition" for retail and investment banks. Maybe it is for central banks who issue their own currency, but not so much for depository institutions like Bank of America. They don't care what currency you use; they just want to find a way to monetize it. People wanted Venmo, so the banks created Zelle. If people start using cryptocurrency, they'll create depository accounts and an internal network for instant payments that cuts out fees. There will always be a niche for this because people want convenience and ease of use -- even if it is antithetical to what Bitcoin is.