Intelligent Playlist based off another Playlist

Someday, are you guys gonna give us the ability to create an intelligent playlist, with the criteria if a song is in another playlist or not?
This would certainly be a game changer for Rekordbox!... and a function desperately needed by us DJ's.
Itunes already offer this ability, and has for years now.
If so, how long will we have to wait??... Estimate.
Thank you so much!