The "bkuptocard" sub-command of gpg --edit-key does not anymore work as it used to work back then when we had a secring.gpg and a pubring.gpg. The problem is that no public subkey packet is created and one has to resort to generate subkey from card. This needs to be fixed.
And while at it: the gpg --card-edit generate command needs an option to only create the signing key, which is the first step in replacing a bricked card with a new card. After that bktocard can be used to restore the encryption subkey.