You can always throw away the armor pieces you dont like and keep the ones you plan on use as vanity, once the system's implemented. I'm quite sure the great majority of the playerbase is saving their DL heavy set, specially the chest armor, eagerly waiting to be able to use it as skin for their most advanced gear!

I just can't see SE giving us an option to trade those armors. They served their end and you just discard them afterward.