local key as smartcard *fallback*

[Raph]

Hi,

When using keytocard, the keyring is informed that the key is now
stored on a smartcard... only (unless removed explicitly).

If the smartcard is unavailable (lost or whatever), is there an *easy*
way to tell the agent to automatically use the local key, if present ?


Basically:
*If* the smartcard is not present,
*Then*
  *If* a local and password-protected version exists,
  *Then* use it as a fallback.


I do understand that smartcard security depends on *not* having the
local key present.
But such a (more flexible) key lookup policy would still be useful in
some situations like for a smoother transition to smartcard or smartcard
used optionally on several computers, ...


Thank you.


Related question:
https://security.stackexchange.com/questions/183226/how-to-force-gpg-to-use-a-keycard-when-it-is-available