It’s confusing because permissionless (public) and permissioned (private) blockchains serve very different needs while people try to look at them through a single lens. Think we need to accept that they are different and calling them all “blockchains” isn’t helpful. They will continue to co-exist and it is unlikely that one “phases” the other out. Banks have no interest in Bitcoin’s blockchain or other public ledgers, it’s simple as that!