We're always looking to make sure we're addressing highly-voted feature requests such as this one when feasible.
However, we do not have current plans to work on the implementation of encrypting external system passwords in Crowd's database.
The main reason for this is that we believe there is no solution that would fully resolve this issue in a secure manner and all known implementations would only give you a false sense of security.
Moreover, introducing database passwords encryption would complicate current functionalities in Crowd, such as backup and restore.
We understand that this will be a disappointment for many, but we remain committed to user-requested features. Please keep the feedback coming!