How about this way of generating a passphrase.
Let's say it has three parts
First part: Some simple word/password which you cannot forget
Second part: Your fingerprint
Third part: Store the third part in the cloud. Now to retrieve it you need a password which will be generated by time-synchronization. Something like Gemalto's token. Simply put these are one-time passwords which are put into a device before they are deployed and only your device and authentication system knows this. Since this is a cloud system you can have ways to recover the password even if the device is lost.

This way even if one part of your key is compromised you still have two levels to break in. So as soon you sense one part is broke you can create a new wallet and continue using it