Hi Alex.
Don't think so. And I believe it would never happen because:
1. There are different encryption Technologies out there. I doubt rekordbox will Support multiple. Therefore rekordbox would Need to have their own.
2. Potential license fees
3. Don't think the CDJ / XDJ will have the power for real time decryption and even have the necessary CPU for it.
4. The Audio processing is time critical. Additional encryption might make it not possible anymore to have real time hot cues or something else without different architecture of CDJ / XDJ.
5. No user demand - As a DJ who want to plug the USB into any CDJ / XDJ out in the Clubs, I wouldn't go down that route and depend on the question does the curren Hardware Support encryption yes or no.
6. And simply - what is the risk not having the Music encrypted. I don't feel a big risk of loss when the USB with Music is stolen. It is not nice - but what is your risk?