[bnny]

It's been a few years, but this requires manually deploying keys and adding/removing users on all your devices. Most use TACACS+ and/or Radius to centrally manage users, which don't support keys in that way (or at least didn't the last time I worked with them.)

[vbernat]

There is an implementation with an extension: https://github.com/MarcJHuber/event-driven-servers/wiki/TACA.... But I don't know if there are any supported clients.

Another possibility would be to use CA certificates for authentication and only TACACS+ for authorization and accounting. Juniper now supports CA certificates. Cisco may in 10 years.