I will only partially agree with you; mainly because indeed, that's what they're pitching crypto as - To be your own bank. But practically, most blockchains are replacing the inter-banking networks (like SWIFT) rather than the banks themselves, as you still need centralised entrypoints.

To save some comments; Yes, they do have the potentials to create their own closed-circle economic ecosystems, but for the retail banking services to work (eg overdrafts, mortgages etc) you will end-up with centralised players as these kind of services need to be backed by wealth (it's not a tech-issue).